ROLLOUT 7 · modelcontextprotocol/python-sdk
modelcontextprotocol__python-sdk-1864
Solved
418 stotal time
18tool calls
20model calls
4,413tokens generated
190,830prompt tokens read
No error recorded
⚠ The request log has 19 model calls but the trace has 21 agent calls, so tokens are listed separately instead of beside each turn.
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System instructions 4,822 characters
You are a principal Python software engineer resolving a repository issue in `/workspace`. Your sole objective is to produce a minimal, root-cause source patch that passes every hidden fail-to-pass and pass-to-pass regression test on the first grading run. ## Critical Environment & Grader Rules 1. **Air-Gapped Sandbox & Available CLI Tools**: No network access. Never run `pip`, `uv`, `conda`, or `git fetch`. Note: `rg` (`ripgrep`) is NOT installed in the container — always use `grep -rn --include="*.py"` for fast exact searches so you never waste a tool call on `command not found`. 2. **Protected Grading Paths**: Before running official verification, the grading harness **strips and reverts all changes** to `tests/`, `test/`, `testing/`, `test_*.py`, `*_test.py`, `conftest.py`, `pyproject.toml`, `setup.cfg`, `pytest.ini`, and `tox.ini`. Every part of your fix MUST reside in non-test production source files. 3. **Untracked File Trap (`git add -N .`)**: `submit_patch` stages ALL untracked files inside `/workspace`! Never leave reproduction or scratch files inside `/workspace` — run reproductions inline via `python3 - <<'PY'` or inside `/tmp/repro.py` in a single `run_command`. 4. **Stdout Truncation Rule**: `run_command` truncates stdout after the first 5,000 characters from the TOP. Always run pytest quietly with short tracebacks: `pytest path/to/test_file.py -k pattern -q --tb=short --no-header` If a test file is large, redirect output to `/tmp/pytest.log` and inspect `tail -n 80 /tmp/pytest.log` so failure tracebacks at the bottom are never cut off. 5. **Strict Pacing Discipline**: `get_status` and `submit_patch` are free and do NOT count toward `max_tool_calls`. Target **16-22 counted tool calls total**, and **begin your first `edit_file` change no later than tool call 15**. Reserve at least 4 calls for verification, `git status --short && git diff`, and submission. ## Execution Protocol ### Phase 1 — Pinpoint Code & Tests Immediately (1-2 tool calls) - The user message already contains `Workspace Layout` — do NOT waste a turn running `ls` on top-level directories. - Run a single compound `run_command` with `grep -rn --include="*.py"` to locate: (a) the exact symbols, error strings, or functions from the problem description, (b) **all parallel or sibling implementations** (for example sync + async variants, `Client` + `AsyncClient`, serializer + deserializer, multiple backends/dialects, base + subclass methods, `__init__.py` / `__all__` exports), and (c) the closest existing unit test files under `tests/`. ### Phase 2 — Deep Read & Spec Anchor (2-5 tool calls) - Use `read_file` with generous `start_line` and `end_line` windows (180-300 lines per call so you read whole modules in fewer calls) on the target function/class, callers, type annotations, and neighboring tests. - Before editing, verify every explicit and implicit requirement from the issue: exact parameter names, defaults, boundary/domain edge cases, exception types/messages, `None` vs empty collection vs falsy (`0`, `False`, `""`) semantics, mutability/copying, and return types. ### Phase 3 — Reproduce Bug in One Call (1 tool call) - Run ONE concise command (`python3 - <<'PY' ... PY` or targeted `pytest ... -q --tb=short --no-header`) via `run_command` to observe the exact pre-fix failure. Do NOT spend multiple tool calls writing separate reproduction scripts. ### Phase 4 — Surgical Implementation Across All Parallel Paths (1-4 tool calls) - Begin editing by tool call 15! Use `edit_file` with 4-6 lines of exact surrounding context copied from `read_file`. - Update ALL parallel codepaths (sync/async, multiple classes/dialects, type hints) consistently so partial fixes do not fail sibling tests. - **2-Strike Edit Rule**: If `edit_file` fails twice on the same block due to whitespace or escaping, do not retry `edit_file` a third time — apply an atomic Python transformation via `run_command` and immediately verify `python3 -m py_compile path/to/file.py`. ### Phase 5 — Edge-Case Verification, Diff Hygiene & Clean Exit (2-4 tool calls) - Run a single compound `run_command` testing both your reproduction + boundary edge cases (`None`, empty input, leading/trailing delimiters, subdomain/prefix boundaries, subclass/async parity) AND the relevant existing `pytest` module(s) with `-q --tb=short --no-header`. - Run `git status --short && git diff` via `run_command`. Confirm: - ZERO untracked (`??`) files in `/workspace` (`rm -f` any untracked workspace files immediately), - ZERO modifications to `tests/` or protected config files (`git checkout -- tests/` if touched), - Minimal, clean diff with valid imports and indentation. - Call `submit_patch` once verification passes, then respond with a brief 2-sentence plain-text summary and make NO further tool calls.
Task prompt 3,632 characters
You are evaluating a software engineering task for repository modelcontextprotocol/python-sdk.
Problem Statement:
URL Parameters Not Decoded in Dynamic Resources
### Initial Checks
- [ ] I confirm that I'm using the latest version of MCP Python SDK
- [x] I confirm that I searched for my issue in https://github.com/modelcontextprotocol/python-sdk/issues before opening this issue
### Description
Dynamic URL resource parameters in MCP protocol are not automatically URL-decoded, causing encoded characters (like %20 for spaces and %C3%A9 for accented characters) to be passed as-is to resource handlers instead of their decoded equivalents.
Here is a simple log for the bug:
- **before**
```
2025-06-17 14:43:44,385 [INFO] kn-graph: Found 0 products matching 'stick%20correcteur%20teint%C3%A9%20anti-imperfections%20rechargeable%20au%20zinc' - (logger.py:226)
```
- **after explicit decode**
```
2025-06-17 14:55:10,173 [INFO] kn-graph: Found 10 products matching 'stick correcteur teinté anti-imperfections rechargeable au zinc' - (logger.py:226)
```
### Example Code
```Python
@mcp.resource("products://search/{product_identifier}")
def find_similar_products(product_identifier: str):
"""
Find similar products based on a given product identifier.
:param product_identifier: The identifier of the product (product name or code).
:return: Similar products or an error message if none are found.
"""
print(product_identifier)
"""
-- walkaround: explicit decoding
from urllib.parse import unquote
print(unquote(product_identifier))
"""
```
### Python & MCP Python SDK
```Text
# uv pip list | grep "mcp"
mcp 1.9.2
# python --version
Python 3.13.4
```
## Task Budget (Session terminates when any budget is exhausted)
- Time allowance: 7.5 minutes
- Tool calls allowance: 30 calls
- Max loop iterations: 40 turns
## Execution Environment Rules
- Single command timeout: 90 seconds (commands exceeding this fail without ending the session)
- Command output limit: 5000 characters
- File view limit: 150 lines per read_file call
- File character limit: 10000 characters per read_file call
- Environment is offline (no network/PyPI access). All repository and test dependencies are ALREADY pre-installed. Do NOT attempt to run pip install or download packages.
## Instructions:
0. All source code is under `/workspace`. Do NOT search outside `/workspace` (e.g. `/usr/`, `/wheels/`, system site-packages). If imports fail, the issue is in the source code under `/workspace`, not in missing system packages.
1. Analyze the problem statement and any provided hints carefully to identify all requested script paths, CLI subcommands, or Python modules.
2. Inspect existing codebase conventions and test files before making edits.
3. Verify your implementation using targeted tests or inline assertions before submitting.
4. Call submit_patch only after your implementation is complete and verified.
5. As your final action, you must return a text-only response reporting your completion to terminate the session.
## Workspace Layout
The repository is located at `/workspace`. Here is the directory tree (up to 3 levels):
```
./CLAUDE.md
./CODE_OF_CONDUCT.md
./CONTRIBUTING.md
./LICENSE
./README.md
./RELEASE.md
./SECURITY.md
./docs
./examples
./mkdocs.yml
./pyproject.toml
./scripts
./scripts/test
./scripts/update_readme_snippets.py
./src
./src/mcp
./src/mcp/__init__.py
./src/mcp/cli
./src/mcp/client
./src/mcp/os
./src/mcp/py.typed
./src/mcp/server
./src/mcp/shared
./src/mcp/types.py
./tests
./uv.lock
```
Turn 1at 23 s229 tokens out3,031 prompt tokens
The user is reporting that dynamic URL resource parameters in the MCP Python SDK are not being URL-decoded.
For example, if a resource is defined as `products://search/{product_identifier}`, and the request comes as `products://search/stick%20correcteur`, the `product_identifier` received by the handler is `stick%20correcteur` instead of `stick correcteur`.
I need to find where dynamic resources are handled and ensure that the parameters extracted from the URL are URL-decoded.
First, I'll search for where resources are defined and handled, specifically looking for the `@mcp.resource` decorator or similar patterns.
TOOL CALL · run_command
{
"command": "grep -rn --include=\"*.py\" \"resource\" src/mcp/server | grep -n \"decorator\" -B 5 -A 5 || grep -rn --include=\"*.py\" \"@mcp.resource\" src/mcp/server || grep -rn --include=\"*.py\" \"resource\" src/mcp/server"
}Result of run_command 1,219 characters
{
"status": "ok",
"stdout": "123-src/mcp/server/fastmcp/server.py:548: meta: Optional metadata dictionary for the resource\n124-src/mcp/server/fastmcp/server.py:551: @server.resource(\"resource://my-resource\")\n125-src/mcp/server/fastmcp/server.py:555: @server.resource(\"resource://my-resource\")\n126-src/mcp/server/fastmcp/server.py:560: @server.resource(\"resource://{city}/weather\")\n127-src/mcp/server/fastmcp/server.py:564: @server.resource(\"resource://{city}/weather\")\n128:src/mcp/server/fastmcp/server.py:572: \"The @resource decorator was used incorrectly. \"\n129-src/mcp/server/fastmcp/server.py:573: \"Did you forget to call it? Use @resource('uri') instead of @resource\"\n130-src/mcp/server/fastmcp/server.py:588: # We need to remove the context_param from the resource function if\n131-src/mcp/server/fastmcp/server.py:598: self._resource_manager.add_template(\n132-src/mcp/server/fastmcp/server.py:610: # Register as regular resource\n133-src/mcp/server/fastmcp/server.py:611: resource = FunctionResource.from_function(\n",
"stderr": "",
"exit_code": 0
}Turn 2at 35 s124 tokens out3,707 prompt tokens
It seems `src/mcp/server/fastmcp/server.py` is the place where `@server.resource` (or `@mcp.resource` if `mcp` is an instance of `FastMCP`) is defined. Let's examine `src/mcp/server/fastmcp/server.py`. I want to see how resources are registered and how they are called.
TOOL CALL · read_file
{
"filepath": "src/mcp/server/fastmcp/server.py",
"start_line": 500
}Result of read_file 5,960 characters
{
"status": "ok",
"filepath": "src/mcp/server/fastmcp/server.py",
"content": "\n Example:\n @mcp.completion()\n async def handle_completion(ref, argument, context):\n if isinstance(ref, ResourceTemplateReference):\n # Return completions based on ref, argument, and context\n return Completion(values=[\"option1\", \"option2\"])\n return None\n \"\"\"\n return self._mcp_server.completion()\n\n def add_resource(self, resource: Resource) -> None:\n \"\"\"Add a resource to the server.\n\n Args:\n resource: A Resource instance to add\n \"\"\"\n self._resource_manager.add_resource(resource)\n\n def resource(\n self,\n uri: str,\n *,\n name: str | None = None,\n title: str | None = None,\n description: str | None = None,\n mime_type: str | None = None,\n icons: list[Icon] | None = None,\n annotations: Annotations | None = None,\n meta: dict[str, Any] | None = None,\n ) -> Callable[[AnyFunction], AnyFunction]:\n \"\"\"Decorator to register a function as a resource.\n\n The function will be called when the resource is read to generate its content.\n The function can return:\n - str for text content\n - bytes for binary content\n - other types will be converted to JSON\n\n If the URI contains parameters (e.g. \"resource://{param}\") or the function\n has parameters, it will be registered as a template resource.\n\n Args:\n uri: URI for the resource (e.g. \"resource://my-resource\" or \"resource://{param}\")\n name: Optional name for the resource\n title: Optional human-readable title for the resource\n description: Optional description of the resource\n mime_type: Optional MIME type for the resource\n meta: Optional metadata dictionary for the resource\n\n Example:\n @server.resource(\"resource://my-resource\")\n def get_data() -> str:\n return \"Hello, world!\"\n\n @server.resource(\"resource://my-resource\")\n async get_data() -> str:\n data = await fetch_data()\n return f\"Hello, world! {data}\"\n\n @server.resource(\"resource://{city}/weather\")\n def get_weather(city: str) -> str:\n return f\"Weather for {city}\"\n\n @server.resource(\"resource://{city}/weather\")\n async def get_weather(city: str) -> str:\n data = await fetch_weather(city)\n return f\"Weather for {city}: {data}\"\n \"\"\"\n # Check if user passed function directly instead of calling decorator\n if callable(uri):\n raise TypeError(\n \"The @resource decorator was used incorrectly. \"\n \"Did you forget to call it? Use @resource('uri') instead of @resource\"\n )\n\n def decorator(fn: AnyFunction) -> AnyFunction:\n # Check if this should be a template\n sig = inspect.signature(fn)\n has_uri_params = \"{\" in uri and \"}\" in uri\n has_func_params = bool(sig.parameters)\n\n if has_uri_params or has_func_params:\n # Check for Context parameter to exclude from validation\n context_param = find_context_parameter(fn)\n\n # Validate that URI params match function params (excluding context)\n uri_params = set(re.findall(r\"{(\\w+)}\", uri))\n # We need to remove the context_param from the resource function if\n # there is any.\n func_params = {p for p in sig.parameters.keys() if p != context_param}\n\n if uri_params != func_params:\n raise ValueError(\n f\"Mismatch between URI parameters {uri_params} and function parameters {func_params}\"\n )\n\n # Register as template\n self._resource_manager.add_template(\n fn=fn,\n uri_template=uri,\n name=name,\n title=title,\n description=description,\n mime_type=mime_type,\n icons=icons,\n annotations=annotations,\n meta=meta,\n )\n else:\n # Register as regular resource\n resource = FunctionResource.from_function(\n fn=fn,\n uri=uri,\n name=name,\n title=title,\n description=description,\n mime_type=mime_type,\n icons=icons,\n annotations=annotations,\n meta=meta,\n )\n self.add_resource(resource)\n return fn\n\n return decorator\n\n def add_prompt(self, prompt: Prompt) -> None:\n \"\"\"Add a prompt to the server.\n\n Args:\n prompt: A Prompt instance to add\n \"\"\"\n self._prompt_manager.add_prompt(prompt)\n\n def prompt(\n self,\n name: str | None = None,\n title: str | None = None,\n description: str | None = None,\n icons: list[Icon] | None = None,\n ) -> Callable[[AnyFunction], AnyFunction]:\n \"\"\"Decorator to register a prompt.\n\n Args:\n name: Optional name for the prompt (defaults to function name)\n title: Optional human-readable title for the prompt\n description: Optional description of what the prompt does\n\n Example:",
"start_line": 500,
"end_line": 649,
"total_lines": 1298,
"is_truncated": true
}Turn 3at 49 s184 tokens out5,266 prompt tokens
The `resource` decorator calls `self._resource_manager.add_template` if it's a template resource. I need to find where `_resource_manager` is defined and how templates are handled when a resource is read. Let's find the `ResourceManager` class. It's likely in `src/mcp/server/fastmcp/resources.py` or similar. Let me check the imports in `src/mcp/server/fastmcp/server.py`. Wait, I didn't see the imports. Let me look at the beginning of `src/mcp/server/fastmcp/server.py`.
TOOL CALL · read_file
{
"end_line": 100,
"filepath": "src/mcp/server/fastmcp/server.py",
"start_line": 1
}Result of read_file 4,314 characters
{
"status": "ok",
"filepath": "src/mcp/server/fastmcp/server.py",
"content": "\"\"\"FastMCP - A more ergonomic interface for MCP servers.\"\"\"\n\nfrom __future__ import annotations\n\nimport inspect\nimport re\nfrom collections.abc import AsyncIterator, Awaitable, Callable, Iterable, Sequence\nfrom contextlib import AbstractAsyncContextManager, asynccontextmanager\nfrom typing import Any, Generic, Literal\n\nimport anyio\nimport pydantic_core\nfrom pydantic import BaseModel\nfrom pydantic.networks import AnyUrl\nfrom pydantic_settings import BaseSettings, SettingsConfigDict\nfrom starlette.applications import Starlette\nfrom starlette.middleware import Middleware\nfrom starlette.middleware.authentication import AuthenticationMiddleware\nfrom starlette.requests import Request\nfrom starlette.responses import Response\nfrom starlette.routing import Mount, Route\nfrom starlette.types import Receive, Scope, Send\n\nfrom mcp.server.auth.middleware.auth_context import AuthContextMiddleware\nfrom mcp.server.auth.middleware.bearer_auth import BearerAuthBackend, RequireAuthMiddleware\nfrom mcp.server.auth.provider import OAuthAuthorizationServerProvider, ProviderTokenVerifier, TokenVerifier\nfrom mcp.server.auth.settings import AuthSettings\nfrom mcp.server.elicitation import ElicitationResult, ElicitSchemaModelT, UrlElicitationResult, elicit_with_validation\nfrom mcp.server.elicitation import elicit_url as _elicit_url\nfrom mcp.server.fastmcp.exceptions import ResourceError\nfrom mcp.server.fastmcp.prompts import Prompt, PromptManager\nfrom mcp.server.fastmcp.resources import FunctionResource, Resource, ResourceManager\nfrom mcp.server.fastmcp.tools import Tool, ToolManager\nfrom mcp.server.fastmcp.utilities.context_injection import find_context_parameter\nfrom mcp.server.fastmcp.utilities.logging import configure_logging, get_logger\nfrom mcp.server.lowlevel.helper_types import ReadResourceContents\nfrom mcp.server.lowlevel.server import LifespanResultT\nfrom mcp.server.lowlevel.server import Server as MCPServer\nfrom mcp.server.lowlevel.server import lifespan as default_lifespan\nfrom mcp.server.session import ServerSession, ServerSessionT\nfrom mcp.server.sse import SseServerTransport\nfrom mcp.server.stdio import stdio_server\nfrom mcp.server.streamable_http import EventStore\nfrom mcp.server.streamable_http_manager import StreamableHTTPSessionManager\nfrom mcp.server.transport_security import TransportSecuritySettings\nfrom mcp.shared.context import LifespanContextT, RequestContext, RequestT\nfrom mcp.types import Annotations, AnyFunction, ContentBlock, GetPromptResult, Icon, ToolAnnotations\nfrom mcp.types import Prompt as MCPPrompt\nfrom mcp.types import PromptArgument as MCPPromptArgument\nfrom mcp.types import Resource as MCPResource\nfrom mcp.types import ResourceTemplate as MCPResourceTemplate\nfrom mcp.types import Tool as MCPTool\n\nlogger = get_logger(__name__)\n\n\nclass Settings(BaseSettings, Generic[LifespanResultT]):\n \"\"\"FastMCP server settings.\n\n All settings can be configured via environment variables with the prefix FASTMCP_.\n For example, FASTMCP_DEBUG=true will set debug=True.\n \"\"\"\n\n model_config = SettingsConfigDict(\n env_prefix=\"FASTMCP_\",\n env_file=\".env\",\n env_nested_delimiter=\"__\",\n nested_model_default_partial_update=True,\n extra=\"ignore\",\n )\n\n # Server settings\n debug: bool\n log_level: Literal[\"DEBUG\", \"INFO\", \"WARNING\", \"ERROR\", \"CRITICAL\"]\n\n # HTTP settings\n host: str\n port: int\n sse_path: str\n message_path: str\n streamable_http_path: str\n\n # StreamableHTTP settings\n json_response: bool\n stateless_http: bool\n \"\"\"Define if the server should create a new transport per request.\"\"\"\n\n # resource settings\n warn_on_duplicate_resources: bool\n\n # tool settings\n warn_on_duplicate_tools: bool\n\n # prompt settings\n warn_on_duplicate_prompts: bool\n\n lifespan: Callable[[FastMCP[LifespanResultT]], AbstractAsyncContextManager[LifespanResultT]] | None\n \"\"\"A async context manager that will be called when the server is started.\"\"\"\n\n auth: AuthSettings | None",
"start_line": 1,
"end_line": 100,
"total_lines": 1298,
"is_truncated": false
}Turn 4at 53 s69 tokens out6,675 prompt tokens
The `ResourceManager` is imported from `mcp.server.fastmcp.resources`. Let's examine `src/mcp/server/fastmcp/resources.py`.
TOOL CALL · read_file
{
"filepath": "src/mcp/server/fastmcp/resources.py"
}Result of read_file 435 characters
{
"status": "error",
"error_type": "FileReadError",
"error_message": "404 Client Error for http+docker://localhost/v1.52/containers/12796e857a4fc9c649b8cb71b3bfb67ce517ce9f0c9f1d1950715aca3302d9cf/archive?path=%2Fworkspace%2Fsrc%2Fmcp%2Fserver%2Ffastmcp%2Fresources.py: Not Found (\"Could not find the file /workspace/src/mcp/server/fastmcp/resources.py in container 12796e857a4fc9c649b8cb71b3bfb67ce517ce9f0c9f1d1950715aca3302d9cf\")"
}Turn 5at 64 s163 tokens out6,977 prompt tokens
Wait, I got a 404 for `src/mcp/server/fastmcp/resources.py`. Let me check the workspace layout again. Workspace Layout: ``` ./src ./src/mcp ./src/mcp/__init__.py ./src/mcp/cli ./src/mcp/client ./src/mcp/os ./src/mcp/py.typed ./src/mcp/server ./src/mcp/shared ./src/mcp/types.py ``` I see `src/mcp/server`. Let me check its contents.
TOOL CALL · run_command
{
"command": "ls -R src/mcp/server"
}Result of run_command 1,339 characters
{
"status": "ok",
"stdout": "src/mcp/server:\n__init__.py\n__main__.py\nauth\nelicitation.py\nexperimental\nfastmcp\nlowlevel\nmodels.py\nsession.py\nsse.py\nstdio.py\nstreamable_http.py\nstreamable_http_manager.py\ntransport_security.py\nvalidation.py\nwebsocket.py\n\nsrc/mcp/server/auth:\n__init__.py\nerrors.py\nhandlers\njson_response.py\nmiddleware\nprovider.py\nroutes.py\nsettings.py\n\nsrc/mcp/server/auth/handlers:\n__init__.py\nauthorize.py\nmetadata.py\nregister.py\nrevoke.py\ntoken.py\n\nsrc/mcp/server/auth/middleware:\n__init__.py\nauth_context.py\nbearer_auth.py\nclient_auth.py\n\nsrc/mcp/server/experimental:\n__init__.py\nrequest_context.py\nsession_features.py\ntask_context.py\ntask_result_handler.py\ntask_support.py\n\nsrc/mcp/server/fastmcp:\n__init__.py\nexceptions.py\nprompts\nresources\nserver.py\ntools\nutilities\n\nsrc/mcp/server/fastmcp/prompts:\n__init__.py\nbase.py\nmanager.py\n\nsrc/mcp/server/fastmcp/resources:\n__init__.py\nbase.py\nresource_manager.py\ntemplates.py\ntypes.py\n\nsrc/mcp/server/fastmcp/tools:\n__init__.py\nbase.py\ntool_manager.py\n\nsrc/mcp/server/fastmcp/utilities:\n__init__.py\ncontext_injection.py\nfunc_metadata.py\nlogging.py\ntypes.py\n\nsrc/mcp/server/lowlevel:\n__init__.py\nexperimental.py\nfunc_inspection.py\nhelper_types.py\nserver.py\n",
"stderr": "",
"exit_code": 0
}Turn 6at 74 s164 tokens out7,711 prompt tokens
Ah, `src/mcp/server/fastmcp/resources` is a directory! Let's see what's inside `src/mcp/server/fastmcp/resources/`. It contains: - `__init__.py` - `base.py` - `resource_manager.py` - `templates.py` - `types.py` The `ResourceManager` is likely in `resource_manager.py` or `__init__.py`. Let me check `src/mcp/server/fastmcp/resources/__init__.py` first.
TOOL CALL · read_file
{
"filepath": "src/mcp/server/fastmcp/resources/__init__.py"
}Result of read_file 669 characters
{
"status": "ok",
"filepath": "src/mcp/server/fastmcp/resources/__init__.py",
"content": "from .base import Resource\nfrom .resource_manager import ResourceManager\nfrom .templates import ResourceTemplate\nfrom .types import (\n BinaryResource,\n DirectoryResource,\n FileResource,\n FunctionResource,\n HttpResource,\n TextResource,\n)\n\n__all__ = [\n \"Resource\",\n \"TextResource\",\n \"BinaryResource\",\n \"FunctionResource\",\n \"FileResource\",\n \"HttpResource\",\n \"DirectoryResource\",\n \"ResourceTemplate\",\n \"ResourceManager\",\n]",
"start_line": 1,
"end_line": 23,
"total_lines": 23,
"is_truncated": false
}Turn 7at 78 s69 tokens out8,086 prompt tokens
Okay, so `ResourceManager` is in `src/mcp/server/fastmcp/resources/resource_manager.py`. Let's examine that file.
TOOL CALL · read_file
{
"filepath": "src/mcp/server/fastmcp/resources/resource_manager.py"
}Result of read_file 4,364 characters
{
"status": "ok",
"filepath": "src/mcp/server/fastmcp/resources/resource_manager.py",
"content": "\"\"\"Resource manager functionality.\"\"\"\n\nfrom __future__ import annotations\n\nfrom collections.abc import Callable\nfrom typing import TYPE_CHECKING, Any\n\nfrom pydantic import AnyUrl\n\nfrom mcp.server.fastmcp.resources.base import Resource\nfrom mcp.server.fastmcp.resources.templates import ResourceTemplate\nfrom mcp.server.fastmcp.utilities.logging import get_logger\nfrom mcp.types import Annotations, Icon\n\nif TYPE_CHECKING:\n from mcp.server.fastmcp.server import Context\n from mcp.server.session import ServerSessionT\n from mcp.shared.context import LifespanContextT, RequestT\n\nlogger = get_logger(__name__)\n\n\nclass ResourceManager:\n \"\"\"Manages FastMCP resources.\"\"\"\n\n def __init__(self, warn_on_duplicate_resources: bool = True):\n self._resources: dict[str, Resource] = {}\n self._templates: dict[str, ResourceTemplate] = {}\n self.warn_on_duplicate_resources = warn_on_duplicate_resources\n\n def add_resource(self, resource: Resource) -> Resource:\n \"\"\"Add a resource to the manager.\n\n Args:\n resource: A Resource instance to add\n\n Returns:\n The added resource. If a resource with the same URI already exists,\n returns the existing resource.\n \"\"\"\n logger.debug(\n \"Adding resource\",\n extra={\n \"uri\": resource.uri,\n \"type\": type(resource).__name__,\n \"resource_name\": resource.name,\n },\n )\n existing = self._resources.get(str(resource.uri))\n if existing:\n if self.warn_on_duplicate_resources:\n logger.warning(f\"Resource already exists: {resource.uri}\")\n return existing\n self._resources[str(resource.uri)] = resource\n return resource\n\n def add_template(\n self,\n fn: Callable[..., Any],\n uri_template: str,\n name: str | None = None,\n title: str | None = None,\n description: str | None = None,\n mime_type: str | None = None,\n icons: list[Icon] | None = None,\n annotations: Annotations | None = None,\n meta: dict[str, Any] | None = None,\n ) -> ResourceTemplate:\n \"\"\"Add a template from a function.\"\"\"\n template = ResourceTemplate.from_function(\n fn,\n uri_template=uri_template,\n name=name,\n title=title,\n description=description,\n mime_type=mime_type,\n icons=icons,\n annotations=annotations,\n meta=meta,\n )\n self._templates[template.uri_template] = template\n return template\n\n async def get_resource(\n self,\n uri: AnyUrl | str,\n context: Context[ServerSessionT, LifespanContextT, RequestT] | None = None,\n ) -> Resource | None:\n \"\"\"Get resource by URI, checking concrete resources first, then templates.\"\"\"\n uri_str = str(uri)\n logger.debug(\"Getting resource\", extra={\"uri\": uri_str})\n\n # First check concrete resources\n if resource := self._resources.get(uri_str):\n return resource\n\n # Then check templates\n for template in self._templates.values():\n if params := template.matches(uri_str):\n try:\n return await template.create_resource(uri_str, params, context=context)\n except Exception as e: # pragma: no cover\n raise ValueError(f\"Error creating resource from template: {e}\")\n\n raise ValueError(f\"Unknown resource: {uri}\")\n\n def list_resources(self) -> list[Resource]:\n \"\"\"List all registered resources.\"\"\"\n logger.debug(\"Listing resources\", extra={\"count\": len(self._resources)})\n return list(self._resources.values())\n\n def list_templates(self) -> list[ResourceTemplate]:\n \"\"\"List all registered templates.\"\"\"\n logger.debug(\"Listing templates\", extra={\"count\": len(self._templates)})\n return list(self._templates.values())",
"start_line": 1,
"end_line": 115,
"total_lines": 115,
"is_truncated": false
}Turn 8at 83 s94 tokens out9,326 prompt tokens
In `ResourceManager.get_resource`, it calls `template.matches(uri_str)` and then `template.create_resource(uri_str, params, context=context)`. Let's check `src/mcp/server/fastmcp/resources/templates.py`.
TOOL CALL · read_file
{
"filepath": "src/mcp/server/fastmcp/resources/templates.py"
}Result of read_file 5,308 characters
{
"status": "ok",
"filepath": "src/mcp/server/fastmcp/resources/templates.py",
"content": "\"\"\"Resource template functionality.\"\"\"\n\nfrom __future__ import annotations\n\nimport inspect\nimport re\nfrom collections.abc import Callable\nfrom typing import TYPE_CHECKING, Any\n\nfrom pydantic import BaseModel, Field, validate_call\n\nfrom mcp.server.fastmcp.resources.types import FunctionResource, Resource\nfrom mcp.server.fastmcp.utilities.context_injection import find_context_parameter, inject_context\nfrom mcp.server.fastmcp.utilities.func_metadata import func_metadata\nfrom mcp.types import Annotations, Icon\n\nif TYPE_CHECKING:\n from mcp.server.fastmcp.server import Context\n from mcp.server.session import ServerSessionT\n from mcp.shared.context import LifespanContextT, RequestT\n\n\nclass ResourceTemplate(BaseModel):\n \"\"\"A template for dynamically creating resources.\"\"\"\n\n uri_template: str = Field(description=\"URI template with parameters (e.g. weather://{city}/current)\")\n name: str = Field(description=\"Name of the resource\")\n title: str | None = Field(description=\"Human-readable title of the resource\", default=None)\n description: str | None = Field(description=\"Description of what the resource does\")\n mime_type: str = Field(default=\"text/plain\", description=\"MIME type of the resource content\")\n icons: list[Icon] | None = Field(default=None, description=\"Optional list of icons for the resource template\")\n annotations: Annotations | None = Field(default=None, description=\"Optional annotations for the resource template\")\n meta: dict[str, Any] | None = Field(default=None, description=\"Optional metadata for this resource template\")\n fn: Callable[..., Any] = Field(exclude=True)\n parameters: dict[str, Any] = Field(description=\"JSON schema for function parameters\")\n context_kwarg: str | None = Field(None, description=\"Name of the kwarg that should receive context\")\n\n @classmethod\n def from_function(\n cls,\n fn: Callable[..., Any],\n uri_template: str,\n name: str | None = None,\n title: str | None = None,\n description: str | None = None,\n mime_type: str | None = None,\n icons: list[Icon] | None = None,\n annotations: Annotations | None = None,\n meta: dict[str, Any] | None = None,\n context_kwarg: str | None = None,\n ) -> ResourceTemplate:\n \"\"\"Create a template from a function.\"\"\"\n func_name = name or fn.__name__\n if func_name == \"<lambda>\":\n raise ValueError(\"You must provide a name for lambda functions\") # pragma: no cover\n\n # Find context parameter if it exists\n if context_kwarg is None: # pragma: no branch\n context_kwarg = find_context_parameter(fn)\n\n # Get schema from func_metadata, excluding context parameter\n func_arg_metadata = func_metadata(\n fn,\n skip_names=[context_kwarg] if context_kwarg is not None else [],\n )\n parameters = func_arg_metadata.arg_model.model_json_schema()\n\n # ensure the arguments are properly cast\n fn = validate_call(fn)\n\n return cls(\n uri_template=uri_template,\n name=func_name,\n title=title,\n description=description or fn.__doc__ or \"\",\n mime_type=mime_type or \"text/plain\",\n icons=icons,\n annotations=annotations,\n meta=meta,\n fn=fn,\n parameters=parameters,\n context_kwarg=context_kwarg,\n )\n\n def matches(self, uri: str) -> dict[str, Any] | None:\n \"\"\"Check if URI matches template and extract parameters.\"\"\"\n # Convert template to regex pattern\n pattern = self.uri_template.replace(\"{\", \"(?P<\").replace(\"}\", \">[^/]+)\")\n match = re.match(f\"^{pattern}$\", uri)\n if match:\n return match.groupdict()\n return None\n\n async def create_resource(\n self,\n uri: str,\n params: dict[str, Any],\n context: Context[ServerSessionT, LifespanContextT, RequestT] | None = None,\n ) -> Resource:\n \"\"\"Create a resource from the template with the given parameters.\"\"\"\n try:\n # Add context to params if needed\n params = inject_context(self.fn, params, context, self.context_kwarg)\n\n # Call function and check if result is a coroutine\n result = self.fn(**params)\n if inspect.iscoroutine(result):\n result = await result\n\n return FunctionResource(\n uri=uri, # type: ignore\n name=self.name,\n title=self.title,\n description=self.description,\n mime_type=self.mime_type,\n icons=self.icons,\n annotations=self.annotations,\n meta=self.meta,\n fn=lambda: result, # Capture result in closure\n )\n except Exception as e:\n raise ValueError(f\"Error creating resource from template: {e}\")",
"start_line": 1,
"end_line": 122,
"total_lines": 122,
"is_truncated": false
}Turn 9at 122 s536 tokens out10,844 prompt tokens
I found the problem. In `ResourceTemplate.matches`, the parameters are extracted using regex but they are not URL-decoded.
```python
def matches(self, uri: str) -> dict[str, Any] | None:
\"\"\"Check if URI matches template and extract parameters.\"\"\"
# Convert template to regex pattern
pattern = self.uri_template.replace(\"{\", \"(?P<\").replace(\"}\", \">[^/]+)\")
match = re.match(f\"^{pattern}$\", uri)
if match:
return match.groupdict()
return None
```
The `match.groupdict()` returns the values exactly as they appear in the `uri` string, which are URL-encoded. I should use `urllib.parse.unquote` to decode them.
Wait, I should check if there are other places where dynamic resources are handled.
The `ResourceManager.get_resource` uses `ResourceTemplate.matches`.
Let's verify this behavior with a reproduction script.
TOOL CALL · run_command
{
"command": "python3 - <<'PY'\nimport asyncio\nfrom mcp.server.fastmcp import FastMCP\nfrom mcp.server.fastmcp.resources import ResourceManager\nfrom urllib.parse import quote\n\nasync def main():\n mcp = FastMCP(\"test-server\")\n \n @mcp.resource(\"products://search/{product_identifier}\")\n def find_similar_products(product_identifier: str):\n return f\"Search for: {product_identifier}\"\n\n # Simulate a request for a URL-encoded product identifier\n product_id = \"stick correcteur teinté\"\n encoded_id = quote(product_id)\n uri = f\"products://search/{encoded_id}\"\n \n print(f\"Requesting URI: {uri}\")\n \n resource = await mcp._resource_manager.get_resource(uri)\n # FunctionResource stores the result of the function in a closure\n result = resource.read()\n \n print(f\"Result: {result}\")\n \n expected = f\"Search for: {product_id}\"\n if result == expected:\n print(\"PASS\")\n else:\n print(f\"FAIL: Expected '{expected}', got '{result}'\")\n\nasyncio.run(main())\nPY\n"
}Result of run_command 576 characters
{
"status": "ok",
"stdout": "Requesting URI: products://search/stick%20correcteur%20teint%C3%A9\nResult: <coroutine object FunctionResource.read at 0x7ddc96637d30>\nFAIL: Expected 'Search for: stick correcteur teinté', got '<coroutine object FunctionResource.read at 0x7ddc96637d30>'\n",
"stderr": "/opt/conda/envs/testbed/lib/python3.12/asyncio/events.py:88: RuntimeWarning: coroutine 'FunctionResource.read' was never awaited\n self._context.run(self._callback, *self._args)\nRuntimeWarning: Enable tracemalloc to get the object allocation traceback\n",
"exit_code": 0
}Turn 10at 132 s283 tokens out11,588 prompt tokens
The `FunctionResource.read` is a coroutine. I should await it.
TOOL CALL · run_command
{
"command": "python3 - <<'PY'\nimport asyncio\nfrom mcp.server.fastmcp import FastMCP\nfrom urllib.parse import quote\n\nasync def main():\n mcp = FastMCP(\"test-server\")\n \n @mcp.resource(\"products://search/{product_identifier}\")\n def find_similar_products(product_identifier: str):\n return f\"Search for: {product_identifier}\"\n\n product_id = \"stick correcteur teinté\"\n encoded_id = quote(product_id)\n uri = f\"products://search/{encoded_id}\"\n \n print(f\"Requesting URI: {uri}\")\n \n resource = await mcp._resource_manager.get_resource(uri)\n result = await resource.read()\n \n print(f\"Result: {result}\")\n \n expected = f\"Search for: {product_id}\"\n if result == expected:\n print(\"PASS\")\n else:\n print(f\"FAIL: Expected '{expected}', got '{result}'\")\n\nasyncio.run(main())\nPY\n"
}Result of run_command 293 characters
{
"status": "ok",
"stdout": "Requesting URI: products://search/stick%20correcteur%20teint%C3%A9\nResult: Search for: stick%20correcteur%20teint%C3%A9\nFAIL: Expected 'Search for: stick correcteur teinté', got 'Search for: stick%20correcteur%20teint%C3%A9'\n",
"stderr": "",
"exit_code": 0
}Turn 11at 153 s427 tokens out11,997 prompt tokens
The reproduction confirms the bug. Now I will fix it in `src/mcp/server/fastmcp/resources/templates.py`.
I need to import `unquote` from `urllib.parse` and use it on the parameters extracted from the URI.
Let's look at `src/mcp/server/fastmcp/resources/templates.py` again.
```python
def matches(self, uri: str) -> dict[str, Any] | None:
\"\"\"Check if URI matches template and extract parameters.\"\"\"
# Convert template to regex pattern
pattern = self.uri_template.replace(\"{\", \"(?P<\").replace(\"}\", \">[^/]+)\")
match = re.match(f\"^{pattern}$\", uri)
if match:
return match.groupdict()
return None
```
I will change it to:
```python
def matches(self, uri: str) -> dict[str, Any] | None:
\"\"\"Check if URI matches template and extract parameters.\"\"\"
# Convert template to regex pattern
pattern = self.uri_template.replace(\"{\", \"(?P<\").replace(\"}\", \">[^/]+)\")
match = re.match(f\"^{pattern}$\", uri)
if match:
params = match.groupdict()
return {k: unquote(v) for k, v in params.items()}
return None
```
Wait, I need to make sure `unquote` is imported.
Let's check the imports in `src/mcp/server/fastmcp/resources/templates.py`.
TOOL CALL · read_file
{
"end_line": 20,
"filepath": "src/mcp/server/fastmcp/resources/templates.py",
"start_line": 1
}Result of read_file 885 characters
{
"status": "ok",
"filepath": "src/mcp/server/fastmcp/resources/templates.py",
"content": "\"\"\"Resource template functionality.\"\"\"\n\nfrom __future__ import annotations\n\nimport inspect\nimport re\nfrom collections.abc import Callable\nfrom typing import TYPE_CHECKING, Any\n\nfrom pydantic import BaseModel, Field, validate_call\n\nfrom mcp.server.fastmcp.resources.types import FunctionResource, Resource\nfrom mcp.server.fastmcp.utilities.context_injection import find_context_parameter, inject_context\nfrom mcp.server.fastmcp.utilities.func_metadata import func_metadata\nfrom mcp.types import Annotations, Icon\n\nif TYPE_CHECKING:\n from mcp.server.fastmcp.server import Context\n from mcp.server.session import ServerSessionT\n from mcp.shared.context import LifespanContextT, RequestT",
"start_line": 1,
"end_line": 20,
"total_lines": 122,
"is_truncated": false
}Turn 12at 161 s131 tokens out12,707 prompt tokens
I'll add `from urllib.parse import unquote` to the imports.
Wait, before I apply the fix, I should check if there are any other places where URIs are matched and parameters extracted.
I'll search for `replace("{",` or `replace("}",` or `.groupdict()` in the whole `src/mcp` directory.
TOOL CALL · run_command
{
"command": "grep -rn --include=\"*.py\" -E \"replace\\(['\\\"]\\{\\['\\\"]|replace\\(['\\\"]\\}\\['\\\"]|\\.groupdict\\(\\)\" src/mcp"
}Result of run_command 147 characters
{
"status": "ok",
"stdout": "src/mcp/server/fastmcp/resources/templates.py:91: return match.groupdict()\n",
"stderr": "",
"exit_code": 0
}Turn 13at 179 s259 tokens out12,904 prompt tokens
It seems `src/mcp/server/fastmcp/resources/templates.py` is the only place.
One more thing: what if the URI template has other parts that are not parameters? The current regex replaces `{` with `(?P<` and `}` with `>[^/]+)`.
Example: `resource://{city}/weather` becomes `resource://(?P<city>[^/]+)/weather`.
The `match.groupdict()` will have `{'city': '...'}`.
If the user provides a URI like `resource://New%20York/weather`, `match.groupdict()` will have `{'city': 'New%20York'}`.
`unquote('New%20York')` will give `'New York'`. This is correct.
Let's apply the fix.
TOOL CALL · edit_file
{
"filepath": "src/mcp/server/fastmcp/resources/templates.py",
"new_string": "import inspect\nimport re\nfrom urllib.parse import unquote\nfrom collections.abc import Callable",
"old_string": "import inspect\nimport re\nfrom collections.abc import Callable"
}Result of edit_file 423 characters
{
"status": "ok",
"filepath": "src/mcp/server/fastmcp/resources/templates.py",
"occurrences": 1,
"strategy": "exact",
"diff": "--- a/src/mcp/server/fastmcp/resources/templates.py\n+++ b/src/mcp/server/fastmcp/resources/templates.py\n@@ -4,6 +4,7 @@\n \n import inspect\n import re\n+from urllib.parse import unquote\n from collections.abc import Callable\n from typing import TYPE_CHECKING, Any\n \n",
"is_truncated": false
}Turn 14at 185 s142 tokens out13,325 prompt tokens
Now let's update the `matches` method.
TOOL CALL · edit_file
{
"filepath": "src/mcp/server/fastmcp/resources/templates.py",
"new_string": " match = re.match(f\\\"^{pattern}$\\\", uri)\\n if match:\\n params = match.groupdict()\\n return {k: unquote(v) for k, v in params.items()}\\n return None",
"old_string": " match = re.match(f\\\"^{pattern}$\\\", uri)\\n if match:\\n return match.groupdict()\\n return None"
}Result of edit_file 643 characters
{
"status": "ok",
"filepath": "src/mcp/server/fastmcp/resources/templates.py",
"occurrences": 1,
"strategy": "unescaped",
"diff": "--- a/src/mcp/server/fastmcp/resources/templates.py\n+++ b/src/mcp/server/fastmcp/resources/templates.py\n@@ -89,7 +89,8 @@\n pattern = self.uri_template.replace(\"{\", \"(?P<\").replace(\"}\", \">[^/]+)\")\n match = re.match(f\"^{pattern}$\", uri)\n if match:\n- return match.groupdict()\n+ params = match.groupdict()\n+ return {k: unquote(v) for k, v in params.items()}\n return None\n \n async def create_resource(\n",
"is_truncated": false
}Turn 15at 199 s280 tokens out13,701 prompt tokens
Now let's run the reproduction script again to verify the fix.
TOOL CALL · run_command
{
"command": "python3 - <<'PY'\nimport asyncio\nfrom mcp.server.fastmcp import FastMCP\nfrom urllib.parse import quote\n\nasync def main():\n mcp = FastMCP(\"test-server\")\n \n @mcp.resource(\"products://search/{product_identifier}\")\n def find_similar_products(product_identifier: str):\n return f\"Search for: {product_identifier}\"\n\n product_id = \"stick correcteur teinté\"\n encoded_id = quote(product_id)\n uri = f\"products://search/{encoded_id}\"\n \n print(f\"Requesting URI: {uri}\")\n \n resource = await mcp._resource_manager.get_resource(uri)\n result = await resource.read()\n \n print(f\"Result: {result}\")\n \n expected = f\"Search for: {product_id}\"\n if result == expected:\n print(\"PASS\")\n else:\n print(f\"FAIL: Expected '{expected}', got '{result}'\")\n\nasyncio.run(main())\nPY\n"
}Result of run_command 184 characters
{
"status": "ok",
"stdout": "Requesting URI: products://search/stick%20correcteur%20teint%C3%A9\nResult: Search for: stick correcteur teinté\nPASS\n",
"stderr": "",
"exit_code": 0
}Turn 16at 282 s1,027 tokens out14,061 prompt tokens
The reproduction script now passes. Now let me double check if there are any other similar patterns.
I saw that `ResourceTemplate.matches` is used in `ResourceManager.get_resource`.
What if the URI template contains characters that are special in regex?
`pattern = self.uri_template.replace("{", "(?P<").replace("}", ">[^/]+)")`
For example, if `self.uri_template` is `resource://{city}/weather.json`.
The `.` in `.json` is a wildcard in regex. It should probably be escaped.
Wait, is this a bug I should fix now, or is it out of scope?
The problem description says "URL Parameters Not Decoded in Dynamic Resources". The regex behavior for non-parameter parts might be existing behavior.
However, if `uri_template` was `products://search/{product_identifier}`, the regex is `^products://(?P<product_identifier>[^/]+)$`.
If the URI is `products://search/abc`, it matches.
If the URI is `products://search/abc/def`, it doesn't match (because of `[^/]+`).
If `uri_template` is `products://{prod}/info`, the regex is `^products://(?P<prod>[^/]+)/info$`.
If URI is `products://abc/info`, it matches.
If URI is `products://abc/def/info`, it doesn't match.
This seems to be the intended design of template matching in this SDK (simple path parameter matching).
But let's check if I should escape the rest of the `uri_template`.
Usually, when converting a template to a regex, you want to escape characters that have special meaning in regex, except for the parts you are intentionally turning into regex groups.
Currently, it does:
`pattern = self.uri_template.replace("{", "(?P<").replace("}", ">[^/]+)")`
If `uri_template` was `resource://{city}.info/weather`, the regex would be `resource://(?P<city>[^/]+).info/weather`.
The `.` in `.info` would match any character.
Given the scope of the issue, I should focus on the decoding of parameters.
Let me also check if there are any other dynamic resources patterns.
The problem statement says:
"Dynamic URL resource parameters in MCP protocol are not automatically URL-decoded, causing encoded characters (like %20 for spaces and %C3%A9 for accented characters) to be passed as-is to resource handlers instead of their decoded equivalents."
I have fixed this by decoding the values in `ResourceTemplate.matches`.
Let's verify if this affects other things.
The `ResourceTemplate.matches` is used to extract parameters which are then passed to the function.
`params = template.matches(uri_str)`
`return await template.create_resource(uri_str, params, context=context)`
`result = self.fn(**params)`
Yes, this is exactly where the issue is.
Let's check for any other potential issues.
In `ResourceTemplate.from_function`, it uses `validate_call(fn)`.
`fn = validate_call(fn)`
This means the parameters are validated against the type hints. If we pass decoded strings to a function expecting strings, it should be fine.
One more thing: `urllib.parse.unquote` by default decodes `%XX` sequences.
For example, `%20` becomes `' '`, `%C3%A9` becomes `'é'`.
Wait, `unquote` behavior:
`unquote("stick%20correcteur%20teint%C3%A9")` -> `'stick correcteur teinté'`
This is exactly what is needed.
Let's check if I should use `unquote_plus` (which also decodes `+` as space).
Usually, for path segments of a URL, `+` is NOT decoded as space (that's for query parameters).
According to RFC 3986, `+` is a reserved character that can appear in a path.
If the SDK is treating `{param}` as a path segment, `unquote` is generally correct. If it's treated as a query param, `unquote_plus` would be used.
Given the URI examples `resource://{city}/weather`, these are path segments.
Let's see if there's any existing test for `ResourceTemplate` that I might have broken.
I'll look for tests in `tests/`.
TOOL CALL · run_command
{
"command": "grep -rn \"ResourceTemplate\" tests/"
}Result of run_command 5,158 characters
{
"status": "ok",
"stdout": "tests/server/fastmcp/test_integration.py:586: from mcp.types import ResourceTemplateReference\ntests/server/fastmcp/test_integration.py:589: ref=ResourceTemplateReference(type=\"ref/resource\", uri=\"github://repos/{owner}/{repo}\"),\ntests/server/fastmcp/test_title.py:9:from mcp.types import Prompt, Resource, ResourceTemplate, Tool, ToolAnnotations\ntests/server/fastmcp/test_title.py:233: template = ResourceTemplate(uriTemplate=\"file://{id}\", name=\"test_template\")\ntests/server/fastmcp/test_title.py:236: template_with_title = ResourceTemplate(uriTemplate=\"file://{id}\", name=\"test_template\", title=\"Test Template\")\ntests/server/fastmcp/resources/test_resource_manager.py:7:from mcp.server.fastmcp.resources import FileResource, FunctionResource, ResourceManager, ResourceTemplate\ntests/server/fastmcp/resources/test_resource_manager.py:100: template = ResourceTemplate.from_function(\ntests/server/fastmcp/resources/test_resource_template.py:8:from mcp.server.fastmcp.resources import FunctionResource, ResourceTemplate\ntests/server/fastmcp/resources/test_resource_template.py:12:class TestResourceTemplate:\ntests/server/fastmcp/resources/test_resource_template.py:13: \"\"\"Test ResourceTemplate functionality.\"\"\"\ntests/server/fastmcp/resources/test_resource_template.py:21: template = ResourceTemplate.from_function(\ntests/server/fastmcp/resources/test_resource_template.py:37: template = ResourceTemplate.from_function(\ntests/server/fastmcp/resources/test_resource_template.py:58: template = ResourceTemplate.from_function(\ntests/server/fastmcp/resources/test_resource_template.py:82: template = ResourceTemplate.from_function(\ntests/server/fastmcp/resources/test_resource_template.py:98: template = ResourceTemplate.from_function(\ntests/server/fastmcp/resources/test_resource_template.py:120: template = ResourceTemplate.from_function(\ntests/server/fastmcp/resources/test_resource_template.py:146: template = ResourceTemplate.from_function(\ntests/server/fastmcp/resources/test_resource_template.py:177: template = ResourceTemplate.from_function(\ntests/server/fastmcp/resources/test_resource_template.py:193:class TestResourceTemplateAnnotations:\ntests/server/fastmcp/resources/test_resource_template.py:204: template = ResourceTemplate.from_function(\ntests/server/fastmcp/resources/test_resource_template.py:217: template = ResourceTemplate.from_function(fn=get_user_data, uri_template=\"resource://users/{user_id}\")\ntests/server/fastmcp/resources/test_resource_template.py:247: template = ResourceTemplate.from_function(\ntests/server/fastmcp/resources/test_resource_template.py:263:class TestResourceTemplateMetadata:\ntests/server/fastmcp/resources/test_resource_template.py:264: \"\"\"Test ResourceTemplate meta handling.\"\"\"\ntests/server/fastmcp/resources/test_resource_template.py:267: \"\"\"Test that ResourceTemplate.from_function() accepts and stores meta parameter.\"\"\"\ntests/server/fastmcp/resources/test_resource_template.py:274: template = ResourceTemplate.from_function(\ntests/server/fastmcp/resources/test_resource_template.py:294: template = ResourceTemplate.from_function(\ntests/server/fastmcp/test_server.py:768:class TestServerResourceTemplates:\ntests/server/test_session.py:27: ResourceTemplateReference,\ntests/server/test_session.py:121: ref: PromptReference | ResourceTemplateReference,\ntests/server/test_completion_with_context.py:16: ResourceTemplateReference,\ntests/server/test_completion_with_context.py:30: ref: PromptReference | ResourceTemplateReference,\ntests/server/test_completion_with_context.py:44: ref=ResourceTemplateReference(type=\"ref/resource\", uri=\"test://resource/{param}\"),\ntests/server/test_completion_with_context.py:64: ref: PromptReference | ResourceTemplateReference,\ntests/server/test_completion_with_context.py:91: ref: PromptReference | ResourceTemplateReference,\ntests/server/test_completion_with_context.py:96: if isinstance(ref, ResourceTemplateReference):\ntests/server/test_completion_with_context.py:115: ref=ResourceTemplateReference(type=\"ref/resource\", uri=\"db://{database}/{table}\"),\ntests/server/test_completion_with_context.py:123: ref=ResourceTemplateReference(type=\"ref/resource\", uri=\"db://{database}/{table}\"),\ntests/server/test_completion_with_context.py:131: ref=ResourceTemplateReference(type=\"ref/resource\", uri=\"db://{database}/{table}\"),\ntests/server/test_completion_with_context.py:145: ref: PromptReference | ResourceTemplateReference,\ntests/server/test_completion_with_context.py:149: if isinstance(ref, ResourceTemplateReference):\ntests/server/test_completion_with_context.py:167: ref=ResourceTemplateReference(type=\"ref/resource\", uri=\"db://{database}/{table}\"),\ntests/server/test_completion_with_context.py:176: ref=ResourceTemplateReference(type=\"ref/resource\", uri=",
"stderr": "",
"exit_code": 0
}Turn 17at 285 s73 tokens out16,591 prompt tokens
I should run the tests to be sure. Especially `tests/server/fastmcp/resources/test_resource_template.py`.
TOOL CALL · run_command
{
"command": "pytest tests/server/fastmcp/resources/test_resource_template.py -q --tb=short --no-header"
}Result of run_command 5,104 characters
{
"status": "ok",
"stdout": "bringing up nodes...\n48 workers [14 items]\n\nscheduling tests via LoadScheduling\n\ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_async_text_resource \ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplateAnnotations::test_template_annotations_in_fastmcp \ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplateMetadata::test_template_created_resources_inherit_metadata \n[gw13]\u001b[36m [ 7%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplateMetadata::test_template_created_resources_inherit_metadata \ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_template_matches \ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplateAnnotations::test_template_with_annotations \ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplateMetadata::test_template_from_function_with_metadata \ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_basemodel_conversion \ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_custom_type_conversion \ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_template_error \ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_async_binary_resource \n[gw5]\u001b[36m [ 14%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_async_binary_resource \ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplateAnnotations::test_template_without_annotations \n[gw10]\u001b[36m [ 21%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplateAnnotations::test_template_without_annotations \ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplateAnnotations::test_template_created_resources_inherit_annotations \n[gw7]\u001b[36m [ 28%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_custom_type_conversion \ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_create_resource \n[gw2]\u001b[36m [ 35%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_create_resource \n[gw12]\u001b[36m [ 42%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplateMetadata::test_template_from_function_with_metadata \n[gw3]\u001b[36m [ 50%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_template_error \n[gw8]\u001b[36m [ 57%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplateAnnotations::test_template_with_annotations \n[gw4]\u001b[36m [ 64%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_async_text_resource \n[gw9]\u001b[36m [ 71%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplateAnnotations::test_template_annotations_in_fastmcp \n[gw11]\u001b[36m [ 78%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplateAnnotations::test_template_created_resources_inherit_annotations \ntests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_template_creation \n[gw0]\u001b[36m [ 85%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_template_creation \n[gw6]\u001b[36m [ 92%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_basemodel_conversion \n[gw1]\u001b[36m [100%] \u001b[0m\u001b[32mPASSED\u001b[0m tests/server/fastmcp/resources/test_resource_template.py::TestResourceTemplate::test_template_matches \n\n\u001b[92m═══════════════════════════════ \u001b[0m\u001b[34minline-snapshot\u001b[0m\u001b[92m ════════════════════════════════\u001b[0m\nINFO: inline-snapshot was disabled because you used xdist. This means that tests\nwith snapshots will continue to run, but snapshot(x) will only return x and \ninline-snapshot will not be able to fix snapshots or generate reports.\n\n\n\n\u001b[32m============================= \u001b[32m\u001b[1m14 passed\u001b[0m\u001b[32m in 24.83s\u001b[0m\u001b[32m ==============================\u001b[0m\n",
"stderr": "",
"exit_code": 0
}Turn 18at 376 s41 tokens out7,162 prompt tokens
All tests passed. I'm confident with the fix. Final check of the diff.
TOOL CALL · run_command
{
"command": "git status --short && git diff"
}Result of run_command 973 characters
{
"status": "ok",
"stdout": " M src/mcp/server/fastmcp/resources/templates.py\ndiff --git a/src/mcp/server/fastmcp/resources/templates.py b/src/mcp/server/fastmcp/resources/templates.py\nindex 89a8ceb..61c5b07 100644\n--- a/src/mcp/server/fastmcp/resources/templates.py\n+++ b/src/mcp/server/fastmcp/resources/templates.py\n@@ -4,6 +4,7 @@ from __future__ import annotations\n \n import inspect\n import re\n+from urllib.parse import unquote\n from collections.abc import Callable\n from typing import TYPE_CHECKING, Any\n \n@@ -88,7 +89,8 @@ class ResourceTemplate(BaseModel):\n pattern = self.uri_template.replace(\"{\", \"(?P<\").replace(\"}\", \">[^/]+)\")\n match = re.match(f\"^{pattern}$\", uri)\n if match:\n- return match.groupdict()\n+ params = match.groupdict()\n+ return {k: unquote(v) for k, v in params.items()}\n return None\n \n async def create_resource(\n",
"stderr": "",
"exit_code": 0
}Turn 19at 378 s18 tokens out7,557 prompt tokens
The diff looks clean and correct.
TOOL CALL · submit_patch
Result of submit_patch 55 characters
{
"status": "ok",
"patch_size": 831,
"files_changed": 1
}Turn 20at 388 s100 tokens out7,614 prompt tokens
The fix has been applied and verified. I have decoded the URL parameters in the `ResourceTemplate.matches` method to ensure that encoded characters in the URI are passed as decoded strings to the resource handlers.
Turn 21at 388 s
Fixed a bug in `ResourceTemplate.matches` where dynamic URL resource parameters were not being URL-decoded, causing encoded characters like `%20` to be passed as-is to resource handlers. Added `urllib.parse.unquote` to decode the extracted parameters.
Model calls (not matched to turns)
Generated tokens 229 tokens · stopped: STOP
The user is reporting that dynamic URL resource parameters in the MCP Python SDK are not being URL-decoded.
For example, if a resource is defined as `products://search/{product_identifier}`, and the request comes as `products://search/stick%20correcteur`, the `product_identifier` received by the handler is `stick%20correcteur` instead of `stick correcteur`.
I need to find where dynamic resources are handled and ensure that the parameters extracted from the URL are URL-decoded.
First, I'll search for where resources are defined and handled, specifically looking for the `@mcp.resource` decorator or similar patterns.<|channel>thought
The user is reporting that dynamic URL resource parameters in the MCP Python SDK are not being URL-decoded.
For example, if a resource is defined as `products://search/{product_identifier}`, and the request comes as `products://search/stick%20correcteur`, the `product_identifier` received by the handler is `stick%20correcteur` instead of `stick correcteur`.
I need to find where dynamic resources are handled and ensure that the parameters extracted from the URL are URL-decoded.
First, I'll search for where resources are defined and handled, specifically looking for the `@mcp.resource` decorator or similar patterns.<channel|><|tool_call>call:run_command{command:<|"|>grep -rn --include="*.py" "resource" src/mcp/server | grep -n "decorator" -B 5 -A 5 || grep -rn --include="*.py" "@mcp.resource" src/mcp/server || grep -rn --include="*.py" "resource" src/mcp/server<|"|>}<tool_call|><|tool_response>
Generated tokens 124 tokens · stopped: STOP
It seems `src/mcp/server/fastmcp/server.py` is the place where `@server.resource` (or `@mcp.resource` if `mcp` is an instance of `FastMCP`) is defined. Let's examine `src/mcp/server/fastmcp/server.py`. I want to see how resources are registered and how they are called.
It seems `src/mcp/server/fastmcp/server.py` is the place where `@server.resource` (or `@mcp.resource` if `mcp` is an instance of `FastMCP`) is defined.
Let's examine `src/mcp/server/fastmcp/server.py`. I want to see how resources are registered and how they are called.
<channel|><|tool_call>call:read_file{filepath:<|"|>src/mcp/server/fastmcp/server.py<|"|>,start_line:500}<tool_call|><|tool_response>
Generated tokens 184 tokens · stopped: STOP
The `resource` decorator calls `self._resource_manager.add_template` if it's a template resource. I need to find where `_resource_manager` is defined and how templates are handled when a resource is read. Let's find the `ResourceManager` class. It's likely in `src/mcp/server/fastmcp/resources.py` or similar. Let me check the imports in `src/mcp/server/fastmcp/server.py`. Wait, I didn't see the imports. Let me look at the beginning of `src/mcp/server/fastmcp/server.py`.
The `resource` decorator calls `self._resource_manager.add_template` if it's a template resource.
I need to find where `_resource_manager` is defined and how templates are handled when a resource is read.
Let's find the `ResourceManager` class. It's likely in `src/mcp/server/fastmcp/resources.py` or similar. Let me check the imports in `src/mcp/server/fastmcp/server.py`.
Wait, I didn't see the imports. Let me look at the beginning of `src/mcp/server/fastmcp/server.py`.<channel|><|tool_call>call:read_file{filepath:<|"|>src/mcp/server/fastmcp/server.py<|"|>,start_line:1,end_line:100}<tool_call|><|tool_response>
Generated tokens 69 tokens · stopped: STOP
The `ResourceManager` is imported from `mcp.server.fastmcp.resources`. Let's examine `src/mcp/server/fastmcp/resources.py`.
The `ResourceManager` is imported from `mcp.server.fastmcp.resources`. Let's examine `src/mcp/server/fastmcp/resources.py`.
<channel|><|tool_call>call:read_file{filepath:<|"|>src/mcp/server/fastmcp/resources.py<|"|>}<tool_call|><|tool_response>
Generated tokens 163 tokens · stopped: STOP
Wait, I got a 404 for `src/mcp/server/fastmcp/resources.py`. Let me check the workspace layout again. Workspace Layout: ``` ./src ./src/mcp ./src/mcp/__init__.py ./src/mcp/cli ./src/mcp/client ./src/mcp/os ./src/mcp/py.typed ./src/mcp/server ./src/mcp/shared ./src/mcp/types.py ``` I see `src/mcp/server`. Let me check its contents.
Wait, I got a 404 for `src/mcp/server/fastmcp/resources.py`. Let me check the workspace layout again.
Workspace Layout:
```
./src
./src/mcp
./src/mcp/__init__.py
./src/mcp/cli
./src/mcp/client
./src/mcp/os
./src/mcp/py.typed
./src/mcp/server
./src/mcp/shared
./src/mcp/types.py
```
I see `src/mcp/server`. Let me check its contents.
<channel|><|tool_call>call:run_command{command:<|"|>ls -R src/mcp/server<|"|>}<tool_call|><|tool_response>
Generated tokens 164 tokens · stopped: STOP
Ah, `src/mcp/server/fastmcp/resources` is a directory! Let's see what's inside `src/mcp/server/fastmcp/resources/`. It contains: - `__init__.py` - `base.py` - `resource_manager.py` - `templates.py` - `types.py` The `ResourceManager` is likely in `resource_manager.py` or `__init__.py`. Let me check `src/mcp/server/fastmcp/resources/__init__.py` first.
Ah, `src/mcp/server/fastmcp/resources` is a directory!
Let's see what's inside `src/mcp/server/fastmcp/resources/`.
It contains:
- `__init__.py`
- `base.py`
- `resource_manager.py`
- `templates.py`
- `types.py`
The `ResourceManager` is likely in `resource_manager.py` or `__init__.py`.
Let me check `src/mcp/server/fastmcp/resources/__init__.py` first.
<channel|><|tool_call>call:read_file{filepath:<|"|>src/mcp/server/fastmcp/resources/__init__.py<|"|>}<tool_call|><|tool_response>
Generated tokens 69 tokens · stopped: STOP
Okay, so `ResourceManager` is in `src/mcp/server/fastmcp/resources/resource_manager.py`. Let's examine that file.
Okay, so `ResourceManager` is in `src/mcp/server/fastmcp/resources/resource_manager.py`. Let's examine that file.
<channel|><|tool_call>call:read_file{filepath:<|"|>src/mcp/server/fastmcp/resources/resource_manager.py<|"|>}<tool_call|><|tool_response>
Generated tokens 94 tokens · stopped: STOP
In `ResourceManager.get_resource`, it calls `template.matches(uri_str)` and then `template.create_resource(uri_str, params, context=context)`. Let's check `src/mcp/server/fastmcp/resources/templates.py`.
In `ResourceManager.get_resource`, it calls `template.matches(uri_str)` and then `template.create_resource(uri_str, params, context=context)`.
Let's check `src/mcp/server/fastmcp/resources/templates.py`.
<channel|><|tool_call>call:read_file{filepath:<|"|>src/mcp/server/fastmcp/resources/templates.py<|"|>}<tool_call|><|tool_response>
Generated tokens 536 tokens · stopped: STOP
I found the problem. In `ResourceTemplate.matches`, the parameters are extracted using regex but they are not URL-decoded.
```python
def matches(self, uri: str) -> dict[str, Any] | None:
\"\"\"Check if URI matches template and extract parameters.\"\"\"
# Convert template to regex pattern
pattern = self.uri_template.replace(\"{\", \"(?P<\").replace(\"}\", \">[^/]+)\")
match = re.match(f\"^{pattern}$\", uri)
if match:
return match.groupdict()
return None
```
The `match.groupdict()` returns the values exactly as they appear in the `uri` string, which are URL-encoded. I should use `urllib.parse.unquote` to decode them.
Wait, I should check if there are other places where dynamic resources are handled.
The `ResourceManager.get_resource` uses `ResourceTemplate.matches`.
Let's verify this behavior with a reproduction script.
I found the problem. In `ResourceTemplate.matches`, the parameters are extracted using regex but they are not URL-decoded.
```python
def matches(self, uri: str) -> dict[str, Any] | None:
\"\"\"Check if URI matches template and extract parameters.\"\"\"
# Convert template to regex pattern
pattern = self.uri_template.replace(\"{\", \"(?P<\").replace(\"}\", \">[^/]+)\")
match = re.match(f\"^{pattern}$\", uri)
if match:
return match.groupdict()
return None
```
The `match.groupdict()` returns the values exactly as they appear in the `uri` string, which are URL-encoded. I should use `urllib.parse.unquote` to decode them.
Wait, I should check if there are other places where dynamic resources are handled.
The `ResourceManager.get_resource` uses `ResourceTemplate.matches`.
Let's verify this behavior with a reproduction script.
<channel|><|tool_call>call:run_command{command:<|"|>python3 - <<'PY'
import asyncio
from mcp.server.fastmcp import FastMCP
from mcp.server.fastmcp.resources import ResourceManager
from urllib.parse import quote
async def main():
mcp = FastMCP("test-server")
@mcp.resource("products://search/{product_identifier}")
def find_similar_products(product_identifier: str):
return f"Search for: {product_identifier}"
# Simulate a request for a URL-encoded product identifier
product_id = "stick correcteur teinté"
encoded_id = quote(product_id)
uri = f"products://search/{encoded_id}"
print(f"Requesting URI: {uri}")
resource = await mcp._resource_manager.get_resource(uri)
# FunctionResource stores the result of the function in a closure
result = resource.read()
print(f"Result: {result}")
expected = f"Search for: {product_id}"
if result == expected:
print("PASS")
else:
print(f"FAIL: Expected '{expected}', got '{result}'")
asyncio.run(main())
PY
<|"|>}<tool_call|><|tool_response>
Generated tokens 283 tokens · stopped: STOP
The `FunctionResource.read` is a coroutine. I should await it.
The `FunctionResource.read` is a coroutine. I should await it.
<channel|><|tool_call>call:run_command{command:<|"|>python3 - <<'PY'
import asyncio
from mcp.server.fastmcp import FastMCP
from urllib.parse import quote
async def main():
mcp = FastMCP("test-server")
@mcp.resource("products://search/{product_identifier}")
def find_similar_products(product_identifier: str):
return f"Search for: {product_identifier}"
product_id = "stick correcteur teinté"
encoded_id = quote(product_id)
uri = f"products://search/{encoded_id}"
print(f"Requesting URI: {uri}")
resource = await mcp._resource_manager.get_resource(uri)
result = await resource.read()
print(f"Result: {result}")
expected = f"Search for: {product_id}"
if result == expected:
print("PASS")
else:
print(f"FAIL: Expected '{expected}', got '{result}'")
asyncio.run(main())
PY
<|"|>}<tool_call|><|tool_response>
Generated tokens 427 tokens · stopped: STOP
The reproduction confirms the bug. Now I will fix it in `src/mcp/server/fastmcp/resources/templates.py`.
I need to import `unquote` from `urllib.parse` and use it on the parameters extracted from the URI.
Let's look at `src/mcp/server/fastmcp/resources/templates.py` again.
```python
def matches(self, uri: str) -> dict[str, Any] | None:
\"\"\"Check if URI matches template and extract parameters.\"\"\"
# Convert template to regex pattern
pattern = self.uri_template.replace(\"{\", \"(?P<\").replace(\"}\", \">[^/]+)\")
match = re.match(f\"^{pattern}$\", uri)
if match:
return match.groupdict()
return None
```
I will change it to:
```python
def matches(self, uri: str) -> dict[str, Any] | None:
\"\"\"Check if URI matches template and extract parameters.\"\"\"
# Convert template to regex pattern
pattern = self.uri_template.replace(\"{\", \"(?P<\").replace(\"}\", \">[^/]+)\")
match = re.match(f\"^{pattern}$\", uri)
if match:
params = match.groupdict()
return {k: unquote(v) for k, v in params.items()}
return None
```
Wait, I need to make sure `unquote` is imported.
Let's check the imports in `src/mcp/server/fastmcp/resources/templates.py`.
The reproduction confirms the bug. Now I will fix it in `src/mcp/server/fastmcp/resources/templates.py`.
I need to import `unquote` from `urllib.parse` and use it on the parameters extracted from the URI.
Let's look at `src/mcp/server/fastmcp/resources/templates.py` again.
```python
def matches(self, uri: str) -> dict[str, Any] | None:
\"\"\"Check if URI matches template and extract parameters.\"\"\"
# Convert template to regex pattern
pattern = self.uri_template.replace(\"{\", \"(?P<\").replace(\"}\", \">[^/]+)\")
match = re.match(f\"^{pattern}$\", uri)
if match:
return match.groupdict()
return None
```
I will change it to:
```python
def matches(self, uri: str) -> dict[str, Any] | None:
\"\"\"Check if URI matches template and extract parameters.\"\"\"
# Convert template to regex pattern
pattern = self.uri_template.replace(\"{\", \"(?P<\").replace(\"}\", \">[^/]+)\")
match = re.match(f\"^{pattern}$\", uri)
if match:
params = match.groupdict()
return {k: unquote(v) for k, v in params.items()}
return None
```
Wait, I need to make sure `unquote` is imported.
Let's check the imports in `src/mcp/server/fastmcp/resources/templates.py`.
<channel|><|tool_call>call:read_file{end_line:20,filepath:<|"|>src/mcp/server/fastmcp/resources/templates.py<|"|>,start_line:1}<tool_call|><|tool_response>
Generated tokens 131 tokens · stopped: STOP
I'll add `from urllib.parse import unquote` to the imports.
Wait, before I apply the fix, I should check if there are any other places where URIs are matched and parameters extracted.
I'll search for `replace("{",` or `replace("}",` or `.groupdict()` in the whole `src/mcp` directory.
I'll add `from urllib.parse import unquote` to the imports.
Wait, before I apply the fix, I should check if there are any other places where URIs are matched and parameters extracted.
I'll search for `replace("{",` or `replace("}",` or `.groupdict()` in the whole `src/mcp` directory.
<channel|><|tool_call>call:run_command{command:<|"|>grep -rn --include="*.py" -E "replace\(['\"]\{\['\"]|replace\(['\"]\}\['\"]|\.groupdict\(\)" src/mcp<|"|>}<tool_call|><|tool_response>
Generated tokens 259 tokens · stopped: STOP
It seems `src/mcp/server/fastmcp/resources/templates.py` is the only place.
One more thing: what if the URI template has other parts that are not parameters? The current regex replaces `{` with `(?P<` and `}` with `>[^/]+)`.
Example: `resource://{city}/weather` becomes `resource://(?P<city>[^/]+)/weather`.
The `match.groupdict()` will have `{'city': '...'}`.
If the user provides a URI like `resource://New%20York/weather`, `match.groupdict()` will have `{'city': 'New%20York'}`.
`unquote('New%20York')` will give `'New York'`. This is correct.
Let's apply the fix.
It seems `src/mcp/server/fastmcp/resources/templates.py` is the only place.
One more thing: what if the URI template has other parts that are not parameters? The current regex replaces `{` with `(?P<` and `}` with `>[^/]+)`.
Example: `resource://{city}/weather` becomes `resource://(?P<city>[^/]+)/weather`.
The `match.groupdict()` will have `{'city': '...'}`.
If the user provides a URI like `resource://New%20York/weather`, `match.groupdict()` will have `{'city': 'New%20York'}`.
`unquote('New%20York')` will give `'New York'`. This is correct.
Let's apply the fix.
<channel|><|tool_call>call:edit_file{filepath:<|"|>src/mcp/server/fastmcp/resources/templates.py<|"|>,new_string:<|"|>import inspect
import re
from urllib.parse import unquote
from collections.abc import Callable<|"|>,old_string:<|"|>import inspect
import re
from collections.abc import Callable<|"|>}<tool_call|><|tool_response>
Generated tokens 142 tokens · stopped: STOP
Now let's update the `matches` method.
Now let's update the `matches` method.
<channel|><|tool_call>call:edit_file{filepath:<|"|>src/mcp/server/fastmcp/resources/templates.py<|"|>,new_string:<|"|> match = re.match(f\"^{pattern}$\", uri)\n if match:\n params = match.groupdict()\n return {k: unquote(v) for k, v in params.items()}\n return None<|"|>,old_string:<|"|> match = re.match(f\"^{pattern}$\", uri)\n if match:\n return match.groupdict()\n return None<|"|>}<tool_call|><|tool_response>
Generated tokens 280 tokens · stopped: STOP
Now let's run the reproduction script again to verify the fix.
Now let's run the reproduction script again to verify the fix.
<channel|><|tool_call>call:run_command{command:<|"|>python3 - <<'PY'
import asyncio
from mcp.server.fastmcp import FastMCP
from urllib.parse import quote
async def main():
mcp = FastMCP("test-server")
@mcp.resource("products://search/{product_identifier}")
def find_similar_products(product_identifier: str):
return f"Search for: {product_identifier}"
product_id = "stick correcteur teinté"
encoded_id = quote(product_id)
uri = f"products://search/{encoded_id}"
print(f"Requesting URI: {uri}")
resource = await mcp._resource_manager.get_resource(uri)
result = await resource.read()
print(f"Result: {result}")
expected = f"Search for: {product_id}"
if result == expected:
print("PASS")
else:
print(f"FAIL: Expected '{expected}', got '{result}'")
asyncio.run(main())
PY
<|"|>}<tool_call|><|tool_response>
Generated tokens 1,027 tokens · stopped: STOP
The reproduction script now passes. Now let me double check if there are any other similar patterns.
I saw that `ResourceTemplate.matches` is used in `ResourceManager.get_resource`.
What if the URI template contains characters that are special in regex?
`pattern = self.uri_template.replace("{", "(?P<").replace("}", ">[^/]+)")`
For example, if `self.uri_template` is `resource://{city}/weather.json`.
The `.` in `.json` is a wildcard in regex. It should probably be escaped.
Wait, is this a bug I should fix now, or is it out of scope?
The problem description says "URL Parameters Not Decoded in Dynamic Resources". The regex behavior for non-parameter parts might be existing behavior.
However, if `uri_template` was `products://search/{product_identifier}`, the regex is `^products://(?P<product_identifier>[^/]+)$`.
If the URI is `products://search/abc`, it matches.
If the URI is `products://search/abc/def`, it doesn't match (because of `[^/]+`).
If `uri_template` is `products://{prod}/info`, the regex is `^products://(?P<prod>[^/]+)/info$`.
If URI is `products://abc/info`, it matches.
If URI is `products://abc/def/info`, it doesn't match.
This seems to be the intended design of template matching in this SDK (simple path parameter matching).
But let's check if I should escape the rest of the `uri_template`.
Usually, when converting a template to a regex, you want to escape characters that have special meaning in regex, except for the parts you are intentionally turning into regex groups.
Currently, it does:
`pattern = self.uri_template.replace("{", "(?P<").replace("}", ">[^/]+)")`
If `uri_template` was `resource://{city}.info/weather`, the regex would be `resource://(?P<city>[^/]+).info/weather`.
The `.` in `.info` would match any character.
Given the scope of the issue, I should focus on the decoding of parameters.
Let me also check if there are any other dynamic resources patterns.
The problem statement says:
"Dynamic URL resource parameters in MCP protocol are not automatically URL-decoded, causing encoded characters (like %20 for spaces and %C3%A9 for accented characters) to be passed as-is to resource handlers instead of their decoded equivalents."
I have fixed this by decoding the values in `ResourceTemplate.matches`.
Let's verify if this affects other things.
The `ResourceTemplate.matches` is used to extract parameters which are then passed to the function.
`params = template.matches(uri_str)`
`return await template.create_resource(uri_str, params, context=context)`
`result = self.fn(**params)`
Yes, this is exactly where the issue is.
Let's check for any other potential issues.
In `ResourceTemplate.from_function`, it uses `validate_call(fn)`.
`fn = validate_call(fn)`
This means the parameters are validated against the type hints. If we pass decoded strings to a function expecting strings, it should be fine.
One more thing: `urllib.parse.unquote` by default decodes `%XX` sequences.
For example, `%20` becomes `' '`, `%C3%A9` becomes `'é'`.
Wait, `unquote` behavior:
`unquote("stick%20correcteur%20teint%C3%A9")` -> `'stick correcteur teinté'`
This is exactly what is needed.
Let's check if I should use `unquote_plus` (which also decodes `+` as space).
Usually, for path segments of a URL, `+` is NOT decoded as space (that's for query parameters).
According to RFC 3986, `+` is a reserved character that can appear in a path.
If the SDK is treating `{param}` as a path segment, `unquote` is generally correct. If it's treated as a query param, `unquote_plus` would be used.
Given the URI examples `resource://{city}/weather`, these are path segments.
Let's see if there's any existing test for `ResourceTemplate` that I might have broken.
I'll look for tests in `tests/`.
The reproduction script now passes. Now let me double check if there are any other similar patterns.
I saw that `ResourceTemplate.matches` is used in `ResourceManager.get_resource`.
What if the URI template contains characters that are special in regex?
`pattern = self.uri_template.replace("{", "(?P<").replace("}", ">[^/]+)")`
For example, if `self.uri_template` is `resource://{city}/weather.json`.
The `.` in `.json` is a wildcard in regex. It should probably be escaped.
Wait, is this a bug I should fix now, or is it out of scope?
The problem description says "URL Parameters Not Decoded in Dynamic Resources". The regex behavior for non-parameter parts might be existing behavior.
However, if `uri_template` was `products://search/{product_identifier}`, the regex is `^products://(?P<product_identifier>[^/]+)$`.
If the URI is `products://search/abc`, it matches.
If the URI is `products://search/abc/def`, it doesn't match (because of `[^/]+`).
If `uri_template` is `products://{prod}/info`, the regex is `^products://(?P<prod>[^/]+)/info$`.
If URI is `products://abc/info`, it matches.
If URI is `products://abc/def/info`, it doesn't match.
This seems to be the intended design of template matching in this SDK (simple path parameter matching).
But let's check if I should escape the rest of the `uri_template`.
Usually, when converting a template to a regex, you want to escape characters that have special meaning in regex, except for the parts you are intentionally turning into regex groups.
Currently, it does:
`pattern = self.uri_template.replace("{", "(?P<").replace("}", ">[^/]+)")`
If `uri_template` was `resource://{city}.info/weather`, the regex would be `resource://(?P<city>[^/]+).info/weather`.
The `.` in `.info` would match any character.
Given the scope of the issue, I should focus on the decoding of parameters.
Let me also check if there are any other dynamic resources patterns.
The problem statement says:
"Dynamic URL resource parameters in MCP protocol are not automatically URL-decoded, causing encoded characters (like %20 for spaces and %C3%A9 for accented characters) to be passed as-is to resource handlers instead of their decoded equivalents."
I have fixed this by decoding the values in `ResourceTemplate.matches`.
Let's verify if this affects other things.
The `ResourceTemplate.matches` is used to extract parameters which are then passed to the function.
`params = template.matches(uri_str)`
`return await template.create_resource(uri_str, params, context=context)`
`result = self.fn(**params)`
Yes, this is exactly where the issue is.
Let's check for any other potential issues.
In `ResourceTemplate.from_function`, it uses `validate_call(fn)`.
`fn = validate_call(fn)`
This means the parameters are validated against the type hints. If we pass decoded strings to a function expecting strings, it should be fine.
One more thing: `urllib.parse.unquote` by default decodes `%XX` sequences.
For example, `%20` becomes `' '`, `%C3%A9` becomes `'é'`.
Wait, `unquote` behavior:
`unquote("stick%20correcteur%20teint%C3%A9")` -> `'stick correcteur teinté'`
This is exactly what is needed.
Let's check if I should use `unquote_plus` (which also decodes `+` as space).
Usually, for path segments of a URL, `+` is NOT decoded as space (that's for query parameters).
According to RFC 3986, `+` is a reserved character that can appear in a path.
If the SDK is treating `{param}` as a path segment, `unquote` is generally correct. If it's treated as a query param, `unquote_plus` would be used.
Given the URI examples `resource://{city}/weather`, these are path segments.
Let's see if there's any existing test for `ResourceTemplate` that I might have broken.
I'll look for tests in `tests/`.
<channel|><|tool_call>call:run_command{command:<|"|>grep -rn "ResourceTemplate" tests/<|"|>}<tool_call|><|tool_response>
Generated tokens 73 tokens · stopped: STOP
I should run the tests to be sure. Especially `tests/server/fastmcp/resources/test_resource_template.py`.
I should run the tests to be sure. Especially `tests/server/fastmcp/resources/test_resource_template.py`.
<channel|><|tool_call>call:run_command{command:<|"|>pytest tests/server/fastmcp/resources/test_resource_template.py -q --tb=short --no-header<|"|>}<tool_call|><|tool_response>
Generated tokens 41 tokens · stopped: STOP
All tests passed. I'm confident with the fix. Final check of the diff.
All tests passed. I'm confident with the fix.
Final check of the diff.<channel|><|tool_call>call:run_command{command:<|"|>git status --short && git diff<|"|>}<tool_call|><|tool_response>
Generated tokens 18 tokens · stopped: STOP
The diff looks clean and correct.
The diff looks clean and correct.
<channel|><|tool_call>call:submit_patch{}<tool_call|><|tool_response>
Patch, tests and logs
Final code change Included
diff --git a/src/mcp/server/fastmcp/resources/templates.py b/src/mcp/server/fastmcp/resources/templates.py
index 89a8ceb..61c5b07 100644
--- a/src/mcp/server/fastmcp/resources/templates.py
+++ b/src/mcp/server/fastmcp/resources/templates.py
@@ -4,6 +4,7 @@ from __future__ import annotations
import inspect
import re
+from urllib.parse import unquote
from collections.abc import Callable
from typing import TYPE_CHECKING, Any
@@ -88,7 +89,8 @@ class ResourceTemplate(BaseModel):
pattern = self.uri_template.replace("{", "(?P<").replace("}", ">[^/]+)")
match = re.match(f"^{pattern}$", uri)
if match:
- return match.groupdict()
+ params = match.groupdict()
+ return {k: unquote(v) for k, v in params.items()}
return None
async def create_resource(
Test output Included
============================= test session starts ============================== created: 48/48 workers 48 workers [12 items] scheduling tests via LoadScheduling tests/server/test_stateless_mode.py::test_stateless_error_message_is_actionable tests/issues/test_973_url_decoding.py::test_template_matches_decodes_accented_characters tests/issues/test_973_url_decoding.py::test_template_matches_decodes_space tests/server/test_stateless_mode.py::test_create_message_fails_in_stateless_mode tests/issues/test_973_url_decoding.py::test_template_matches_decodes_complex_phrase tests/server/test_stateless_mode.py::test_stateful_mode_does_not_raise_stateless_error [gw0] [ 8%] PASSED tests/issues/test_973_url_decoding.py::test_template_matches_decodes_space tests/issues/test_973_url_decoding.py::test_template_matches_preserves_plus_sign [gw1] [ 16%] PASSED tests/issues/test_973_url_decoding.py::test_template_matches_decodes_accented_characters tests/server/test_stateless_mode.py::test_list_roots_fails_in_stateless_mode tests/server/test_stateless_mode.py::test_elicit_form_fails_in_stateless_mode [gw6] [ 25%] PASSED tests/server/test_stateless_mode.py::test_elicit_form_fails_in_stateless_mode [gw12] [ 33%] PASSED tests/server/test_stateless_mode.py::test_stateful_mode_does_not_raise_stateless_error tests/server/test_stateless_mode.py::test_exception_has_method_attribute [gw10] [ 41%] PASSED tests/server/test_stateless_mode.py::test_exception_has_method_attribute [gw2] [ 50%] PASSED tests/issues/test_973_url_decoding.py::test_template_matches_decodes_complex_phrase tests/server/test_stateless_mode.py::test_elicit_url_fails_in_stateless_mode [gw7] [ 58%] PASSED tests/server/test_stateless_mode.py::test_elicit_url_fails_in_stateless_mode [gw8] [ 66%] PASSED tests/server/test_stateless_mode.py::test_stateless_error_message_is_actionable tests/server/test_stateless_mode.py::test_elicit_deprecated_fails_in_stateless_mode [gw9] [ 75%] PASSED tests/server/test_stateless_mode.py::test_elicit_deprecated_fails_in_stateless_mode [gw5] [ 83%] PASSED tests/server/test_stateless_mode.py::test_create_message_fails_in_stateless_mode [gw4] [ 91%] PASSED tests/server/test_stateless_mode.py::test_list_roots_fails_in_stateless_mode [gw3] [100%] PASSED tests/issues/test_973_url_decoding.py::test_template_matches_preserves_plus_sign ═══════════════════════════════ inline-snapshot ════════════════════════════════ INFO: inline-snapshot was disabled because you used xdist. This means that tests with snapshots will continue to run, but snapshot(x) will only return x and inline-snapshot will not be able to fix snapshots or generate reports. ==================================== PASSES ==================================== - generated xml file: /tmp/rebench-grade-a7a93251b83b4ec49a55bcd6123bdc52.xml -- =========================== short test summary info ============================ PASSED tests/issues/test_973_url_decoding.py::test_template_matches_decodes_space PASSED tests/issues/test_973_url_decoding.py::test_template_matches_decodes_accented_characters PASSED tests/server/test_stateless_mode.py::test_elicit_form_fails_in_stateless_mode PASSED tests/server/test_stateless_mode.py::test_stateful_mode_does_not_raise_stateless_error PASSED tests/server/test_stateless_mode.py::test_exception_has_method_attribute PASSED tests/issues/test_973_url_decoding.py::test_template_matches_decodes_complex_phrase PASSED tests/server/test_stateless_mode.py::test_elicit_url_fails_in_stateless_mode PASSED tests/server/test_stateless_mode.py::test_stateless_error_message_is_actionable PASSED tests/server/test_stateless_mode.py::test_elicit_deprecated_fails_in_stateless_mode PASSED tests/server/test_stateless_mode.py::test_create_message_fails_in_stateless_mode PASSED tests/server/test_stateless_mode.py::test_list_roots_fails_in_stateless_mode PASSED tests/issues/test_973_url_decoding.py::test_template_matches_preserves_plus_sign ============================= 12 passed in 25.67s ==============================
Test errors Included
Test report (JUnit) Included
<?xml version="1.0" encoding="utf-8"?><testsuites name="pytest tests"><testsuite name="pytest" errors="0" failures="0" skipped="0" tests="12" time="25.673" timestamp="2026-11-14T03:40:45.902115+00:00" hostname="be7db8d13f6c"><testcase classname="tests.issues.test_973_url_decoding" name="test_template_matches_decodes_accented_characters" time="0.003" /><testcase classname="tests.issues.test_973_url_decoding" name="test_template_matches_decodes_space" time="0.003" /><testcase classname="tests.issues.test_973_url_decoding" name="test_template_matches_decodes_complex_phrase" time="0.026" /><testcase classname="tests.server.test_stateless_mode" name="test_elicit_form_fails_in_stateless_mode" time="0.002" /><testcase classname="tests.server.test_stateless_mode" name="test_stateful_mode_does_not_raise_stateless_error" time="0.026" /><testcase classname="tests.server.test_stateless_mode" name="test_exception_has_method_attribute" time="0.002" /><testcase classname="tests.server.test_stateless_mode" name="test_elicit_url_fails_in_stateless_mode" time="0.002" /><testcase classname="tests.server.test_stateless_mode" name="test_stateless_error_message_is_actionable" time="0.123" /><testcase classname="tests.server.test_stateless_mode" name="test_elicit_deprecated_fails_in_stateless_mode" time="0.002" /><testcase classname="tests.server.test_stateless_mode" name="test_create_message_fails_in_stateless_mode" time="0.224" /><testcase classname="tests.server.test_stateless_mode" name="test_list_roots_fails_in_stateless_mode" time="0.002" /><testcase classname="tests.issues.test_973_url_decoding" name="test_template_matches_preserves_plus_sign" time="0.003" /></testsuite></testsuites>
Agent log Included
[ 0.0s] 📋 System Prompt: You are a principal Python software engineer resolving a repository issue in `/workspace`.
[ 0.0s] 🎯 Task Prompt: You are evaluating a software engineering task for repository
modelcontextprotocol/python-sdk.
[ 15.6s] 💭 (623 chars) "The user is reporting that dynamic URL resource parameters in the MCP Python SDK are not
being URL-decoded.
For example,..."
[ 15.6s] 🔧 run_command grep -rn --include="*.py" "resource" src/mcp/server | grep -n "decorator" -B 5 -
[ 15.7s] → 123-src/mcp/server/fastmcp/server.py:548: meta: Optional metadata dictionary for the resource
[ 28.1s] 💭 (270 chars) "It seems `src/mcp/server/fastmcp/server.py` is the place where `@server.resource` (or
`@mcp.resource` if `mcp` is an ins..."
[ 28.1s] 📖 read_file (src/mcp/server/fastmcp/server.py)
[ 28.2s] ✓ {'status': 'ok', 'filepath': 'src/mcp/server/fastmcp/server.py', 'content': '\n Example:\n
@mcp.comple…
[ 42.2s] 💭 (475 chars) "The `resource` decorator calls `self._resource_manager.add_template` if it's a template
resource.
I need to find where `..."
[ 42.2s] 📖 read_file (src/mcp/server/fastmcp/server.py)
[ 42.3s] ✓ {'status': 'ok', 'filepath': 'src/mcp/server/fastmcp/server.py', 'content': '"""FastMCP - A more
ergonomic interface for…
[ 45.8s] 💭 (123 chars) "The `ResourceManager` is imported from `mcp.server.fastmcp.resources`. Let's examine
`src/mcp/server/fastmcp/resources.p..."
[ 45.8s] 📖 read_file (src/mcp/server/fastmcp/resources.py)
[ 45.9s] ❌ {'status': 'error', 'error_type': 'FileReadError', 'error_message': '404 Client Error for
http+docker://localhost/v1.52/…
[ 56.7s] 💭 (333 chars) "Wait, I got a 404 for `src/mcp/server/fastmcp/resources.py`. Let me check the workspace
layout again.
Workspace Layout:..."
[ 56.7s] 🔧 run_command ls -R src/mcp/server
[ 56.8s] → src/mcp/server:
[ 66.6s] 💭 (354 chars) "Ah, `src/mcp/server/fastmcp/resources` is a directory!
Let's see what's inside `src/mcp/server/fastmcp/resources/`.
It ..."
[ 66.6s] 📖 read_file (src/mcp/server/fastmcp/resources/__init__.py)
[ 66.7s] ✓ {'status': 'ok', 'filepath': 'src/mcp/server/fastmcp/resources/__init__.py', 'content': 'from .base
import Resource\nfro…
[ 70.4s] 💭 (113 chars) "Okay, so `ResourceManager` is in `src/mcp/server/fastmcp/resources/resource_manager.py`.
Let's examine that file."
[ 70.4s] 📖 read_file (src/mcp/server/fastmcp/resources/resource_manager.py)
[ 70.4s] ✓ {'status': 'ok', 'filepath': 'src/mcp/server/fastmcp/resources/resource_manager.py', 'content':
'"""Resource manager fun…
[ 75.6s] 💭 (204 chars) "In `ResourceManager.get_resource`, it calls `template.matches(uri_str)` and then
`template.create_resource(uri_str, para..."
[ 75.6s] 📖 read_file (src/mcp/server/fastmcp/resources/templates.py)
[ 75.6s] ✓ {'status': 'ok', 'filepath': 'src/mcp/server/fastmcp/resources/templates.py', 'content': '"""Resource
template functiona…
[ 115.2s] 💭 (897 chars) "I found the problem. In `ResourceTemplate.matches`, the parameters are extracted using regex
but they are not URL-decode..."
[ 115.2s] 🔧 run_command (34 lines) python3 - <<'PY'
[ 116.2s] → Requesting URI: products://search/stick%20correcteur%20teint%C3%A9
[ 125.0s] 💭 (62 chars) "The `FunctionResource.read` is a coroutine. I should await it."
[ 125.0s] 🔧 run_command (31 lines) python3 - <<'PY'
[ 125.3s] → Requesting URI: products://search/stick%20correcteur%20teint%C3%A9
[ 146.1s] 💭 (1293 chars) "The reproduction confirms the bug. Now I will fix it in
`src/mcp/server/fastmcp/resources/templates.py`.
I need to impor..."
[ 146.1s] 📖 read_file (src/mcp/server/fastmcp/resources/templates.py)
[ 146.1s] ✓ {'status': 'ok', 'filepath': 'src/mcp/server/fastmcp/resources/templates.py', 'content': '"""Resource
template functiona…
[ 153.6s] 💭 (286 chars) "I'll add `from urllib.parse import unquote` to the imports.
Wait, before I apply the fix, I should check if there are a..."
[ 153.6s] 🔧 run_command grep -rn --include="*.py" -E "replace\(['\"]\{['\"]|replace\(['\"]\}['\"]|\.gr
[ 153.7s] → src/mcp/server/fastmcp/resources/templates.py:91: return match.groupdict()
[ 171.6s] 💭 (571 chars) "It seems `src/mcp/server/fastmcp/resources/templates.py` is the only place.
One more thing: what if the URI template ha..."
[ 171.6s] ✏️ edit_file (src/mcp/server/fastmcp/resources/templates.py)
[ 171.7s] ✓ {'status': 'ok', 'filepath': 'src/mcp/server/fastmcp/resources/templates.py', 'occurrences': 1,
'strategy': 'exact', 'di…
[ 177.6s] 💭 (38 chars) "Now let's update the `matches` method."
[ 177.6s] ✏️ edit_file (src/mcp/server/fastmcp/resources/templates.py)
[ 177.9s] ✓ {'status': 'ok', 'filepath': 'src/mcp/server/fastmcp/resources/templates.py', 'occurrences': 1,
'strategy': 'unescaped',…
[ 192.1s] 💭 (62 chars) "Now let's run the reproduction script again to verify the fix."
[ 192.1s] 🔧 run_command (31 lines) python3 - <<'PY'
[ 192.4s] → Requesting URI: products://search/stick%20correcteur%20teint%C3%A9
[ 274.7s] 💭 (3743 chars) "The reproduction script now passes. Now let me double check if there are any other similar
patterns.
I saw that `Resour..."
[ 274.7s] 🔧 run_command grep -rn "ResourceTemplate" tests/
[ 274.8s] → tests/server/fastmcp/test_integration.py:586: from mcp.types import ResourceTemplateReference
[ 278.3s] 💭 (105 chars) "I should run the tests to be sure. Especially
`tests/server/fastmcp/resources/test_resource_template.py`."
[ 278.3s] 🔧 run_command pytest tests/server/fastmcp/resources/test_resource_template.py -q --tb=short --
[ 304.0s] → bringing up nodes...
[ 369.0s] 💭 (70 chars) "All tests passed. I'm confident with the fix.
Final check of the diff."
[ 369.0s] 🔧 run_command git status --short && git diff
[ 369.0s] → M src/mcp/server/fastmcp/resources/templates.py
[ 370.8s] 💭 (33 chars) "The diff looks clean and correct."
[ 370.8s] 🤖 submit_patch
[ 370.9s] → submit_patch: {"status": "ok", "patch_size": 831, "files_changed": 1}
[ 381.2s] 💭 (214 chars) "The fix has been applied and verified. I have decoded the URL parameters in the
`ResourceTemplate.matches` method to ens..."
[ 381.2s] ✅ Agent finished: Fixed a bug in `ResourceTemplate.matches` where dynamic URL resource parameters were not
being URL-decoded, causing encoded characters like `%20` to be passed as-is to resource handlers. Added `urllib...
Native result row
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"duration_seconds": 418.21,
"error": null,
"grade": {
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"competition_junit_ok": true,
"error": null,
"required_issues_count": 0,
"resolved": true,
"status_counts": {
"PASSED": 12
},
"strict_clean_patch": true,
"test_exit_code": 0
},
"instance_id": "modelcontextprotocol__python-sdk-1864",
"pass_idx": 0,
"patch_chars": 831,
"phase1_seconds": 390.73,
"repo": "modelcontextprotocol/python-sdk",
"request_log_path": "/kaggle-root/working/r31/rollouts_X/requests/modelcontextprotocol__python-sdk-1864__p0__r7.jsonl",
"resolved": true,
"rollout_idx": 7,
"run_key": "modelcontextprotocol__python-sdk-1864__p0__r7",
"strict_clean_patch": true,
"tool_calls": 18,
"total_llm_calls": 20,
"trace_path": "/kaggle-root/working/r31/rollouts_X/traces/trace_modelcontextprotocol__python-sdk-1864__p0__r7.json"
}