Apply suggestions from code review

Co-authored-by: Douwe Maan <[email protected]>

Author: ChuckJonas

docs/mcp/client.md

@@ -231,9 +231,9 @@ calculator_server = MCPServerSSE(
 agent = Agent('openai:gpt-4o', toolsets=[weather_server, calculator_server])
 ```
 
-## Tool Metadata
+## Tool `meta`, `annotations` & `output_schema`
 
-MCP tools often include metadata that provides additional information about the tool's characteristics, which can use useful in filtering and middleware.  This metadata is available in the [`ToolDefinition.metadata`][pydantic_ai.tools.ToolDefinition.metadata] field.
+MCP tools often include metadata that provides additional information about the tool's characteristics, which can use useful in [`toolset filtering`][pydantic_ai.toolsets.FilteredToolset] and middleware.  These properties are available in the [`ToolDefinition.metadata`][pydantic_ai.tools.ToolDefinition.metadata].
 
 ## Custom TLS / SSL configuration
 

pydantic_ai_slim/pydantic_ai/mcp.py

@@ -254,7 +254,11 @@ async def get_tools(self, ctx: RunContext[Any]) -> dict[str, ToolsetTool[Any]]:
                     name=name,
                     description=mcp_tool.description,
                     parameters_json_schema=mcp_tool.inputSchema,
-                    metadata=mcp_tool.meta,
+                    metadata={
+                        'meta': mcp_tool.meta,
+                        'annotations': mcp_tool.annotations.model_dump() if mcp_tool.annotations else None,
+                        'output_schema': mcp_tool.outputSchema or None,
+                    } 
                 ),
             )
             for mcp_tool in await self.list_tools()

pydantic_ai_slim/pydantic_ai/tools.py

@@ -489,7 +489,7 @@ class ToolDefinition:
     """
 
     metadata: dict[str, Any] | None = None
-    """Tool metadata, primarily used for filtering and tool behavior customization.
+    """Tool metadata that can be set by the toolset this tool came from. It is not sent to the model, but can be used for filtering and tool behavior customization.
 
     For MCP tools, this contains the `_meta` field from the tool definition.
     """

tests/mcp_server.py

@@ -11,14 +11,15 @@
     SamplingMessage,
     TextContent,
     TextResourceContents,
+    ToolAnnotations,
 )
 from pydantic import AnyUrl, BaseModel
 
 mcp = FastMCP('Pydantic AI MCP Server')
 log_level = 'unset'
 
 
-@mcp.tool()
+@mcp.tool(annotations=ToolAnnotations(title='Celsius to Fahrenheit'))
 async def celsius_to_fahrenheit(celsius: float) -> float:
     """Convert Celsius to Fahrenheit.
 

tests/test_logfire.py

@@ -387,6 +387,7 @@ async def my_ret(x: int) -> str:
                                 'strict': None,
                                 'sequential': False,
                                 'kind': 'function',
+                                'metadata': None,
                             }
                         ],
                         'builtin_tools': [],
@@ -780,6 +781,7 @@ class MyOutput:
                                 'strict': None,
                                 'sequential': False,
                                 'kind': 'output',
+                                'metadata': None,
                             }
                         ],
                         'allow_text_output': False,

tests/test_mcp.py

@@ -1251,6 +1251,22 @@ async def test_tool_returning_multiple_items(allow_model_requests: None, agent:
         )
 
 
+async def test_tool_metadata_extraction():
+    """Test that MCP tool metadata is properly extracted into ToolDefinition."""
+
+    server = MCPServerStdio('python', ['-m', 'tests.mcp_server'])
+    async with server:
+        ctx = RunContext(deps=None, model=TestModel(), usage=RunUsage())
+        tools = [tool.tool_def for tool in (await server.get_tools(ctx)).values()]
+        # find `celsius_to_fahrenheit`
+        celsius_to_fahrenheit = next(tool for tool in tools if tool.name == 'celsius_to_fahrenheit')
+        assert celsius_to_fahrenheit.metadata is not None
+        assert celsius_to_fahrenheit.metadata.get('annotations') is not None
+        assert celsius_to_fahrenheit.metadata.get('annotations', {}).get('title', None) == 'Celsius to Fahrenheit'
+        assert celsius_to_fahrenheit.metadata.get('output_schema') is not None
+        assert celsius_to_fahrenheit.metadata.get('output_schema', {}).get('type', None) == 'object'
+
+
 async def test_client_sampling(run_context: RunContext[int]):
     server = MCPServerStdio('python', ['-m', 'tests.mcp_server'])
     server.sampling_model = TestModel(custom_output_text='sampling model response')