fix: make MCP list tools lenient

litellm/experimental_mcp_client/client.py

@@ -43,6 +43,8 @@ from mcp.types import (
     ListResourceTemplatesResult,
     ListResourcesRequest,
     ListResourcesResult,
+    ListToolsRequest,
+    ListToolsResult,
     Prompt,
     ResourceTemplate,
     TextContent,
@@ -91,6 +93,10 @@ def _first_non_cancelled_cause(exc: BaseException) -> Optional[BaseException]:
 TSessionResult = TypeVar("TSessionResult")
 
 
+class _LenientListToolsResult(ListToolsResult):
+    tools: List[MCPTool] = Field(default_factory=list)
+
+
 class _LenientListPromptsResult(ListPromptsResult):
     prompts: List[Prompt] = Field(default_factory=list)
 
@@ -531,7 +537,10 @@ class MCPClient:
         )
 
         async def _list_tools_operation(session: ClientSession):
-            return await session.list_tools()
+            return await session.send_request(
+                ClientRequest(ListToolsRequest()),
+                _LenientListToolsResult,
+            )
 
         try:
             result = await self.run_with_session(_list_tools_operation)

tests/test_litellm/experimental_mcp_client/test_mcp_client.py

@@ -18,6 +18,7 @@ from mcp.types import (
     ListPromptsRequest,
     ListResourceTemplatesRequest,
     ListResourcesRequest,
+    ListToolsRequest,
 )
 from litellm.types.mcp import MCPAuth, MCPStdioConfig, MCPTransport
 
@@ -30,6 +31,9 @@ class _MissingListResultSession:
         self.requests.append((request, result_type))
         return result_type.model_validate({})
 
+    async def list_tools(self):
+        raise AssertionError("strict list_tools should not be used")
+
     async def list_prompts(self):
         raise AssertionError("strict list_prompts should not be used")
 
@@ -74,6 +78,7 @@ class TestMCPClient:
     @pytest.mark.parametrize(
         ("client_method", "request_type"),
         [
+            ("list_tools", ListToolsRequest),
             ("list_prompts", ListPromptsRequest),
             ("list_resources", ListResourcesRequest),
             ("list_resource_templates", ListResourceTemplatesRequest),