fix: missing mcp otel attributes (#29554)

litellm/integrations/otel/model/payloads.py

@@ -340,7 +340,7 @@ class MCPToolCallSpanData:
     def from_standard_logging_payload(
         cls, payload: "StandardLoggingPayload", capture_content: bool = False
     ) -> "MCPToolCallSpanData":
-        meta = cast(Mapping[str, object], payload.get("mcp_tool_call_metadata") or {})
+        meta = _mcp_tool_call_metadata(cast(Mapping[str, object], payload))
         return cls(
             operation=resolve_operation(as_str(payload.get("call_type"))),
             method=MCPMethod.TOOLS_CALL.value,
@@ -363,11 +363,22 @@ class MCPToolCallSpanData:
         )
 
 
+def _mcp_tool_call_metadata(payload: Mapping[str, object]) -> Mapping[str, object]:
+    """The MCP gateway's tool-call metadata, which lives under
+    ``StandardLoggingPayload.metadata`` (a ``StandardLoggingMetadata`` key), not
+    at the payload's top level."""
+    metadata = payload.get("metadata")
+    if not isinstance(metadata, Mapping):
+        return {}
+    meta = metadata.get("mcp_tool_call_metadata")
+    return meta if isinstance(meta, Mapping) else {}
+
+
 def is_mcp_tool_call(payload: Mapping[str, object]) -> bool:
     """Whether a closed request's payload is an MCP tool call rather than an LLM
     call — true when the MCP gateway stamped its tool-call metadata, or the call
     type says so on a path that hasn't populated the metadata yet."""
-    return bool(payload.get("mcp_tool_call_metadata")) or (
+    return bool(_mcp_tool_call_metadata(payload)) or (
         payload.get("call_type") == "call_mcp_tool"
     )
 

tests/test_litellm/integrations/otel/test_otel_v2_logger.py

@@ -249,15 +249,17 @@ def _mcp_payload(**overrides):
         "status": "success",
         "litellm_call_id": "mcp_1",
         "response_cost": 0.01,
-        "metadata": {"user_api_key_team_id": "t1"},
-        "hidden_params": {},
-        "mcp_tool_call_metadata": {
-            "name": "get_weather",
-            "arguments": {"city": "Paris"},
-            "result": {"temp_c": 21},
-            "mcp_server_name": "weather-mcp",
-            "mcp_session_id": "sess-abc123",
+        "metadata": {
+            "user_api_key_team_id": "t1",
+            "mcp_tool_call_metadata": {
+                "name": "get_weather",
+                "arguments": {"city": "Paris"},
+                "result": {"temp_c": 21},
+                "mcp_server_name": "weather-mcp",
+                "mcp_session_id": "sess-abc123",
+            },
         },
+        "hidden_params": {},
     }
     payload.update(overrides)
     return payload
@@ -302,7 +304,7 @@ def test_mcp_tool_call_stateless_omits_session_id():
     ``mcp.session.id`` rather than stamping an empty or ``None`` value."""
     logger, exporter = _logger()
     payload = _mcp_payload()
-    del payload["mcp_tool_call_metadata"]["mcp_session_id"]
+    del payload["metadata"]["mcp_tool_call_metadata"]["mcp_session_id"]
     asyncio.run(
         logger.async_log_success_event(
             {"standard_logging_object": payload}, None, None, None
@@ -360,6 +362,31 @@ def test_mcp_tool_call_deduped_on_repeat():
     assert len(exporter.get_finished_spans()) == 1
 
 
+def test_mcp_tool_call_metadata_read_from_nested_metadata_not_top_level():
+    """``mcp_tool_call_metadata`` lives under ``StandardLoggingPayload.metadata``;
+    a top-level copy (the pre-fix shape the reader used to look at) must be ignored
+    so the reader can't silently regress to producing an empty ``tools/call`` span
+    with no session id, tool name, or server name."""
+    logger, exporter = _logger()
+    payload = _mcp_payload()
+    # Move the real metadata to the top level only, mirroring the old buggy read
+    # location. ``call_type`` still classifies this as an MCP call, so the span is
+    # emitted, but none of its fields are reachable from the wrong nesting level.
+    payload["mcp_tool_call_metadata"] = payload["metadata"].pop(
+        "mcp_tool_call_metadata"
+    )
+    asyncio.run(
+        logger.async_log_success_event(
+            {"standard_logging_object": payload}, None, None, None
+        )
+    )
+    (span,) = exporter.get_finished_spans()
+    assert span.name == "tools/call"
+    assert "mcp.session.id" not in span.attributes
+    assert "gen_ai.tool.name" not in span.attributes
+    assert LiteLLM.MCP_SERVER_NAME not in span.attributes
+
+
 def test_pre_call_idempotent_keeps_first_span():
     """A retried call may re-enter ``pre_call`` with the same call id; the first
     span (with the true start time) is kept, not replaced."""

tests/test_litellm/integrations/otel/test_otel_v2_sources_of_truth.py

@@ -195,15 +195,17 @@ def _mcp_payload(capture=False, **overrides):
         "status": "success",
         "litellm_call_id": "mcp_call_1",
         "response_cost": 0.01,
-        "metadata": {"user_api_key_team_id": "t1"},
-        "hidden_params": {},
-        "mcp_tool_call_metadata": {
-            "name": "get_weather",
-            "arguments": {"city": "Paris"},
-            "result": {"temp_c": 21},
-            "mcp_server_name": "weather-mcp",
-            "mcp_session_id": "sess-abc123",
+        "metadata": {
+            "user_api_key_team_id": "t1",
+            "mcp_tool_call_metadata": {
+                "name": "get_weather",
+                "arguments": {"city": "Paris"},
+                "result": {"temp_c": 21},
+                "mcp_server_name": "weather-mcp",
+                "mcp_session_id": "sess-abc123",
+            },
         },
+        "hidden_params": {},
     }
     payload.update(overrides)
     return payload