code review

Author: vbarda

src/mcp/server/fastmcp/server.py

@@ -10,7 +10,7 @@
     asynccontextmanager,
 )
 from itertools import chain
-from typing import Any, Generic, Literal, overload
+from typing import Any, Generic, Literal
 
 import anyio
 import pydantic_core
@@ -315,42 +315,31 @@ async def read_resource(self, uri: AnyUrl | str) -> Iterable[ReadResourceContent
             logger.error(f"Error reading resource {uri}: {e}")
             raise ResourceError(str(e))
 
-    @overload
-    def add_tool(self, fn: Tool) -> None: ...
+    def add_tool_instance(self, tool: Tool) -> None:
+        """Add a Tool instance to the server."""
+        self._tool_manager.add_tool_instance(tool)
 
-    @overload
     def add_tool(
         self,
         fn: AnyFunction,
         name: str | None = None,
         description: str | None = None,
         annotations: ToolAnnotations | None = None,
-    ) -> None: ...
-
-    def add_tool(
-        self,
-        fn: AnyFunction | Tool,
-        name: str | None = None,
-        description: str | None = None,
-        annotations: ToolAnnotations | None = None,
     ) -> None:
         """Add a tool to the server.
 
         The tool function can optionally request a Context object by adding a parameter
         with the Context type annotation. See the @tool decorator for examples.
 
         Args:
-            fn: The function to register as a tool or a Tool instance
+            fn: The function to register as a tool
             name: Optional name for the tool (defaults to function name)
             description: Optional description of what the tool does
             annotations: Optional ToolAnnotations providing additional tool information
         """
-        if isinstance(fn, Tool):
-            self._tool_manager.add_tool(fn)
-        else:
-            self._tool_manager.add_tool(
-                fn, name=name, description=description, annotations=annotations
-            )
+        self._tool_manager.add_tool(
+            fn, name=name, description=description, annotations=annotations
+        )
 
     def tool(
         self,

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

@@ -1,7 +1,7 @@
 from __future__ import annotations as _annotations
 
 from collections.abc import Callable
-from typing import TYPE_CHECKING, Any, overload
+from typing import TYPE_CHECKING, Any
 
 from mcp.server.fastmcp.exceptions import ToolError
 from mcp.server.fastmcp.tools.base import Tool
@@ -31,42 +31,28 @@ def list_tools(self) -> list[Tool]:
         """List all registered tools."""
         return list(self._tools.values())
 
-    @overload
-    def add_tool(
-        self,
-        fn: Tool,
-    ) -> Tool: ...
+    def add_tool_instance(self, tool: Tool) -> Tool:
+        """Add a Tool instance to the server."""
+        existing = self._tools.get(tool.name)
+        if existing:
+            if self.warn_on_duplicate_tools:
+                logger.warning(f"Tool already exists: {tool.name}")
+            return existing
+        self._tools[tool.name] = tool
+        return tool
 
-    @overload
     def add_tool(
         self,
         fn: Callable[..., Any],
         name: str | None = None,
         description: str | None = None,
         annotations: ToolAnnotations | None = None,
-    ) -> Tool: ...
-
-    def add_tool(
-        self,
-        fn: Callable[..., Any] | Tool,
-        name: str | None = None,
-        description: str | None = None,
-        annotations: ToolAnnotations | None = None,
     ) -> Tool:
         """Add a tool to the server."""
-        if isinstance(fn, Tool):
-            tool = fn
-        else:
-            tool = Tool.from_function(
-                fn, name=name, description=description, annotations=annotations
-            )
-        existing = self._tools.get(tool.name)
-        if existing:
-            if self.warn_on_duplicate_tools:
-                logger.warning(f"Tool already exists: {tool.name}")
-            return existing
-        self._tools[tool.name] = tool
-        return tool
+        tool = Tool.from_function(
+            fn, name=name, description=description, annotations=annotations
+        )
+        return self.add_tool_instance(tool)
 
     async def call_tool(
         self,

tests/server/fastmcp/test_tool_manager.py

@@ -32,7 +32,7 @@ def add(a: int, b: int) -> int:
         assert tool.parameters["properties"]["a"]["type"] == "integer"
         assert tool.parameters["properties"]["b"]["type"] == "integer"
 
-    def test_add_tool_directly(self):
+    def test_add_tool_instance(self):
         manager = ToolManager()
 
         def add(a: int, b: int) -> int:
@@ -54,7 +54,7 @@ class AddArguments(ArgModelBase):
             context_kwarg=None,
             annotations=None,
         )
-        manager.add_tool(original_tool)
+        manager.add_tool_instance(original_tool)
         saved_tool = manager.get_tool("add")
         assert saved_tool == original_tool