Path and Query bug fixes and tests and example.

Author: beaterblank

README.md

@@ -269,7 +269,9 @@ Resources are how you expose data to LLMs. They're similar to GET endpoints in a
 
 <!-- snippet-source examples/snippets/servers/basic_resource.py -->
 ```python
-from mcp.server.fastmcp import FastMCP
+from typing import Annotated
+
+from mcp.server.fastmcp import FastMCP, Path, Query
 
 mcp = FastMCP(name="Resource Example")
 
@@ -381,6 +383,26 @@ def get_weather_data(
             weather_info += f"\nDay {day}: {forecast_temp}{temp_unit}"
 
     return weather_info
+
+
+@mcp.resource("api://data/{user_id}/{region}/{city}/{file_path:path}")
+def resource_fn(
+    # Path parameters
+    user_id: Annotated[int, Path(gt=0, description="User ID")],  # explicit Path
+    region,  # inferred path # type: ignore
+    city: str,  # inferred path
+    file_path: str,  # inferred path {file_path:path}
+    # Required query parameter (no default)
+    version: int,
+    # Optional query parameters (defaults or Query(...))
+    format: Annotated[str, Query("json", description="Output format")],
+    include_metadata: bool = False,
+    tags: list[str] = [],
+    lang: str = "en",
+    debug: bool = False,
+    precision: float = 0.5,
+) -> str:
+    return f"{user_id}/{region}/{city}/{file_path}"
 ```
 
 _Full example: [examples/snippets/servers/basic_resource.py](https://github.com/modelcontextprotocol/python-sdk/blob/main/examples/snippets/servers/basic_resource.py)_

examples/snippets/servers/basic_resource.py

@@ -1,4 +1,6 @@
-from mcp.server.fastmcp import FastMCP
+from typing import Annotated
+
+from mcp.server.fastmcp import FastMCP, Path, Query
 
 mcp = FastMCP(name="Resource Example")
 
@@ -110,3 +112,23 @@ def get_weather_data(
             weather_info += f"\nDay {day}: {forecast_temp}{temp_unit}"
 
     return weather_info
+
+
+@mcp.resource("api://data/{user_id}/{region}/{city}/{file_path:path}")
+def resource_fn(
+    # Path parameters
+    user_id: Annotated[int, Path(gt=0, description="User ID")],  # explicit Path
+    region,  # inferred path # type: ignore
+    city: str,  # inferred path
+    file_path: str,  # inferred path {file_path:path}
+    # Required query parameter (no default)
+    version: int,
+    # Optional query parameters (defaults or Query(...))
+    format: Annotated[str, Query("json", description="Output format")],
+    include_metadata: bool = False,
+    tags: list[str] = [],
+    lang: str = "en",
+    debug: bool = False,
+    precision: float = 0.5,
+) -> str:
+    return f"{user_id}/{region}/{city}/{file_path}"

src/mcp/server/fastmcp/__init__.py

@@ -5,7 +5,8 @@
 from mcp.types import Icon
 
 from .server import Context, FastMCP
+from .utilities.param_functions import Path, Query
 from .utilities.types import Audio, Image
 
 __version__ = version("mcp")
-__all__ = ["FastMCP", "Context", "Image", "Audio", "Icon"]
+__all__ = ["FastMCP", "Context", "Image", "Audio", "Icon", "Path", "Query"]

src/mcp/server/fastmcp/utilities/param_functions.py

@@ -2,7 +2,7 @@
 from typing import Annotated, Any
 
 from pydantic.version import VERSION as PYDANTIC_VERSION
-from typing_extensions import Doc, deprecated
+from typing_extensions import Doc
 
 from mcp.server.fastmcp.utilities import params
 
@@ -258,7 +258,6 @@ def Path(  # noqa: PLR0913
         max_digits=max_digits,
         decimal_places=decimal_places,
         examples=examples,
-        deprecated=deprecated,  # type: ignore
         include_in_schema=include_in_schema,
         json_schema_extra=json_schema_extra,
     )
@@ -455,16 +454,6 @@ def Query(  # noqa: PLR0913
             """
         ),
     ] = None,
-    deprecated: Annotated[
-        deprecated | str | bool | None,
-        Doc(
-            """
-            Mark this parameter field as deprecated.
-
-            It will affect the generated OpenAPI (e.g. visible at `/docs`).
-            """
-        ),
-    ] = None,
     include_in_schema: Annotated[
         bool,
         Doc(
@@ -484,19 +473,6 @@ def Query(  # noqa: PLR0913
             """
         ),
     ] = None,
-    **extra: Annotated[
-        Any,
-        Doc(
-            """
-            Include extra fields used by the JSON Schema.
-            """
-        ),
-        deprecated(
-            """
-            The `extra` kwargs is deprecated. Use `json_schema_extra` instead.
-            """
-        ),
-    ],
 ) -> Any:
     return params.Query(
         default=default,
@@ -521,8 +497,6 @@ def Query(  # noqa: PLR0913
         max_digits=max_digits,
         decimal_places=decimal_places,
         examples=examples,
-        deprecated=deprecated,
         include_in_schema=include_in_schema,
         json_schema_extra=json_schema_extra,
-        **extra,
     )

src/mcp/server/fastmcp/utilities/param_validation.py

@@ -7,8 +7,21 @@
 from collections.abc import Callable
 from typing import Annotated, Any, get_args, get_origin
 
+from pydantic.version import VERSION as PYDANTIC_VERSION
+
 from mcp.server.fastmcp.utilities.convertors import CONVERTOR_TYPES, Convertor
-from mcp.server.fastmcp.utilities.params import Path
+from mcp.server.fastmcp.utilities.params import Path, Query
+
+PYDANTIC_VERSION_MINOR_TUPLE = tuple(int(x) for x in PYDANTIC_VERSION.split(".")[:2])
+PYDANTIC_V2 = PYDANTIC_VERSION_MINOR_TUPLE[0] == 2
+
+if not PYDANTIC_V2:
+    from pydantic.fields import Undefined  # type: ignore[attr-defined]
+else:
+    from pydantic.v1.fields import Undefined
+
+# difference between not given not needed, not given maybe needed.
+_Unset: Any = Undefined  # type: ignore
 
 
 def validate_and_sync_params(
@@ -65,6 +78,10 @@ def _extract_function_params(
                 for meta in args[1:]:
                     if isinstance(meta, Path):
                         explicit_path.add(name)
+                    if isinstance(meta, Query):
+                        if meta.default is not Undefined:
+                            fn_defaults[name] = meta.default
+
         fn_param_types[name] = base_type
 
         # IGNORE TYPES caused a circular import with Context so using it as a string

src/mcp/server/fastmcp/utilities/params.py

@@ -4,7 +4,6 @@
 
 from pydantic.fields import FieldInfo
 from pydantic.version import VERSION as PYDANTIC_VERSION
-from typing_extensions import deprecated
 
 PYDANTIC_VERSION_MINOR_TUPLE = tuple(int(x) for x in PYDANTIC_VERSION.split(".")[:2])
 PYDANTIC_V2 = PYDANTIC_VERSION_MINOR_TUPLE[0] == 2
@@ -52,7 +51,6 @@ def __init__(  # noqa: PLR0913
         max_digits: int | None = _Unset,
         decimal_places: int | None = _Unset,
         examples: list[Any] | None = None,
-        deprecated: deprecated | str | bool | None = None,
         include_in_schema: bool = True,
         json_schema_extra: dict[str, Any] | None = None,
     ):
@@ -78,10 +76,6 @@ def __init__(  # noqa: PLR0913
         if examples is not None:
             kwargs["examples"] = examples
         current_json_schema_extra = json_schema_extra
-        if PYDANTIC_VERSION_MINOR_TUPLE < (2, 7):
-            self.deprecated = deprecated
-        else:
-            kwargs["deprecated"] = deprecated
         if PYDANTIC_V2:
             kwargs.update(
                 {
@@ -134,7 +128,6 @@ def __init__(  # noqa: PLR0913
         max_digits: int | None = _Unset,
         decimal_places: int | None = _Unset,
         examples: list[Any] | None = None,
-        deprecated: deprecated | str | bool | None = None,
         include_in_schema: bool = True,
         json_schema_extra: dict[str, Any] | None = None,
     ):
@@ -163,7 +156,6 @@ def __init__(  # noqa: PLR0913
             allow_inf_nan=allow_inf_nan,
             max_digits=max_digits,
             decimal_places=decimal_places,
-            deprecated=deprecated,
             examples=examples,
             include_in_schema=include_in_schema,
             json_schema_extra=json_schema_extra,
@@ -199,7 +191,6 @@ def __init__(  # noqa: PLR0913
         max_digits: int | None = _Unset,
         decimal_places: int | None = _Unset,
         examples: list[Any] | None = None,
-        deprecated: deprecated | str | bool | None = None,
         include_in_schema: bool = True,
         json_schema_extra: dict[str, Any] | None = None,
     ):
@@ -226,7 +217,6 @@ def __init__(  # noqa: PLR0913
             allow_inf_nan=allow_inf_nan,
             max_digits=max_digits,
             decimal_places=decimal_places,
-            deprecated=deprecated,
             examples=examples,
             include_in_schema=include_in_schema,
             json_schema_extra=json_schema_extra,

tests/server/fastmcp/resources/test_resource_template.py

@@ -1,10 +1,10 @@
 import json
-from typing import Any
+from typing import Annotated, Any
 
 import pytest
 from pydantic import BaseModel
 
-from mcp.server.fastmcp import FastMCP
+from mcp.server.fastmcp import FastMCP, Path, Query
 from mcp.server.fastmcp.resources import FunctionResource, ResourceTemplate
 from mcp.types import Annotations
 
@@ -606,3 +606,50 @@ def get_item(item_id: str) -> str:
         # Verify the resource works correctly
         content = await resource.read()
         assert content == "Item 123"
+
+    def test_full_parameter_inference(self):
+        """Test MCP path and query parameter inference: path, required query, optional query."""
+
+        # Function under test
+        def resource_fn(
+            # Path parameters
+            user_id: Annotated[int, Path(gt=0, description="User ID")],  # explicit Path
+            region,  # inferred path # type: ignore
+            city: str,  # inferred path
+            file_path: str,  # inferred path {file_path:path}
+            # Required query parameter (no default)
+            version: int,
+            # Optional query parameters (defaults or Query(...))
+            format: Annotated[str, Query("json", description="Output format")],
+            include_metadata: bool = False,
+            tags: list[str] = [],
+            lang: str = "en",
+            debug: bool = False,
+            precision: float = 0.5,
+        ) -> str:
+            return f"{user_id}/{region}/{city}/{file_path}"
+
+        # Create resource template
+        template = ResourceTemplate.from_function(
+            fn=resource_fn,  # type: ignore
+            uri_template="api://data/{user_id}/{region}/{city}/{file_path:path}",
+            name="full_resource",
+        )
+
+        # --- Assertions ---
+
+        # Path parameters
+        assert template.path_params == {"user_id", "region", "city", "file_path"}
+
+        # Required query parameters (no default)
+        assert template.required_query_params == {"version"}
+
+        # Optional query parameters (have default or Query)
+        assert template.optional_query_params == {
+            "include_metadata",
+            "tags",
+            "format",
+            "lang",
+            "debug",
+            "precision",
+        }