fix(mcp): hand listed tool metadata to pre-call hooks on the local registry path

OpenAPI-generated and legacy local-registry tools dispatch through execute_mcp_tool's
local branch, which called pre_call_tool_check without the cached MCPTool. Agent 365
therefore received bare {"name"} payloads for those tools while managed-server tools
carried description and inputSchema. Both local call sites now pass get_listed_tool

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm/proxy/_experimental/mcp_server/server.py

@@ -3119,6 +3119,7 @@ if MCP_AVAILABLE:
                 server=mcp_server,
                 raw_headers=raw_headers,
                 litellm_logging_obj=litellm_logging_obj,
+                tool=global_mcp_server_manager.get_listed_tool(mcp_server, original_tool_name),
             )
             # `pre_call_tool_check` may return guardrail-modified
             # arguments; honor them on the local path too.
@@ -3225,6 +3226,7 @@ if MCP_AVAILABLE:
                     server=prefix_server,
                     raw_headers=raw_headers,
                     litellm_logging_obj=litellm_logging_obj,
+                    tool=global_mcp_server_manager.get_listed_tool(prefix_server, original_tool_name),
                 )
                 if "arguments" in hook_result:
                     arguments = hook_result["arguments"]  # pyright: ignore[reportAny]  # hook returns untyped args

tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_server.py

@@ -17,6 +17,7 @@ from mcp.types import (
     TextContent,
     TextResourceContents,
 )
+from mcp.types import Tool as MCPTool
 
 from litellm.proxy._types import (
     LiteLLM_MCPServerTable,
@@ -7159,6 +7160,58 @@ async def test_execute_mcp_tool_sets_model_in_model_call_details():
     assert litellm_logging_obj.model == "MCP: list_pets"
 
 
+@pytest.mark.asyncio
+async def test_execute_mcp_tool_hands_openapi_listed_tool_metadata_to_pre_call_hooks():
+    """OpenAPI-generated tools dispatch through the local registry, so the pre-call hooks must get the
+    listed description and input schema on that path too, not only on the managed-server path."""
+    from litellm.proxy._experimental.mcp_server import server as mcp_module
+
+    petstore = MCPServer(
+        server_id="petstore-id",
+        name="petstore",
+        server_name="petstore",
+        transport=MCPTransport.http,
+        url=None,
+        spec_path="https://example.com/petstore.yaml",
+    )
+    schema = {"type": "object", "properties": {"limit": {"type": "integer"}}}
+    mcp_module.global_mcp_tool_registry.register_tool(
+        name="petstore-list_pets", description="List the pets", input_schema=schema, handler=lambda: None
+    )
+    manager = mcp_module.global_mcp_server_manager
+    manager._create_prefixed_tools(
+        [MCPTool(name="list_pets", description="List the pets", inputSchema=schema)], petstore
+    )
+    pre_call_tool_check = AsyncMock(return_value={})
+
+    try:
+        with (
+            patch.object(manager, "_get_mcp_server_from_tool_name", return_value=petstore),
+            patch.object(manager, "pre_call_tool_check", new=pre_call_tool_check),
+            patch(
+                "litellm.proxy._experimental.mcp_server.server._handle_local_mcp_tool",
+                new=AsyncMock(return_value=[]),
+            ),
+            patch(
+                "litellm.proxy._experimental.mcp_server.server.MCPRequestHandler.is_tool_allowed",
+                return_value=True,
+            ),
+        ):
+            await mcp_module.execute_mcp_tool(
+                name="petstore-list_pets",
+                arguments={"limit": 10},
+                allowed_mcp_servers=[petstore],
+                start_time=datetime.now(),
+                user_api_key_auth=UserAPIKeyAuth(api_key="sk-user", user_id="alice"),
+            )
+    finally:
+        mcp_module.global_mcp_tool_registry.unregister_tools_with_prefix("petstore-")
+        manager._listed_tools_by_server_id.pop(petstore.server_id, None)
+
+    handed_tool = pre_call_tool_check.call_args.kwargs["tool"]
+    assert handed_tool is not None and (handed_tool.description, handed_tool.inputSchema) == ("List the pets", schema)
+
+
 @pytest.mark.asyncio
 async def test_execute_mcp_tool_rest_unresolved_prefixed_name_routes_to_requested_server():
     """A prefixed REST name that resolves to no tool must still dispatch to the server_id.