feat: add tool metadata in decorator

Author: mat-octave

src/mcp/server/fastmcp/server.py

@@ -290,6 +290,7 @@ async def list_tools(self) -> list[MCPTool]:
                 outputSchema=info.output_schema,
                 annotations=info.annotations,
                 icons=info.icons,
+                _meta=info.meta
             )
             for info in tools
         ]
@@ -363,6 +364,7 @@ def add_tool(
         description: str | None = None,
         annotations: ToolAnnotations | None = None,
         icons: list[Icon] | None = None,
+        meta: dict[str, Any] | None = None,
         structured_output: bool | None = None,
     ) -> None:
         """Add a tool to the server.
@@ -388,6 +390,7 @@ def add_tool(
             description=description,
             annotations=annotations,
             icons=icons,
+            meta=meta,
             structured_output=structured_output,
         )
 
@@ -409,6 +412,7 @@ def tool(
         description: str | None = None,
         annotations: ToolAnnotations | None = None,
         icons: list[Icon] | None = None,
+        meta: dict[str, Any] | None = None,
         structured_output: bool | None = None,
     ) -> Callable[[AnyFunction], AnyFunction]:
         """Decorator to register a tool.
@@ -456,6 +460,7 @@ def decorator(fn: AnyFunction) -> AnyFunction:
                 description=description,
                 annotations=annotations,
                 icons=icons,
+                meta=meta,
                 structured_output=structured_output,
             )
             return fn

src/mcp/server/fastmcp/tools/base.py

@@ -34,6 +34,7 @@ class Tool(BaseModel):
     context_kwarg: str | None = Field(None, description="Name of the kwarg that should receive context")
     annotations: ToolAnnotations | None = Field(None, description="Optional annotations for the tool")
     icons: list[Icon] | None = Field(default=None, description="Optional list of icons for this tool")
+    meta: dict[str, Any] | None = Field(default=None, description="Optional metadata for this tool")
 
     @cached_property
     def output_schema(self) -> dict[str, Any] | None:
@@ -49,6 +50,7 @@ def from_function(
         context_kwarg: str | None = None,
         annotations: ToolAnnotations | None = None,
         icons: list[Icon] | None = None,
+        meta: dict[str, Any] | None = None,
         structured_output: bool | None = None,
     ) -> Tool:
         """Create a Tool from a function."""
@@ -81,6 +83,7 @@ def from_function(
             context_kwarg=context_kwarg,
             annotations=annotations,
             icons=icons,
+            meta=meta
         )
 
     async def run(

src/mcp/server/fastmcp/tools/tool_manager.py

@@ -50,6 +50,7 @@ def add_tool(
         description: str | None = None,
         annotations: ToolAnnotations | None = None,
         icons: list[Icon] | None = None,
+        meta: dict[str, Any] | None = None,
         structured_output: bool | None = None,
     ) -> Tool:
         """Add a tool to the server."""
@@ -60,6 +61,7 @@ def add_tool(
             description=description,
             annotations=annotations,
             icons=icons,
+            meta=meta,
             structured_output=structured_output,
         )
         existing = self._tools.get(tool.name)