Python: Propagate user-supplied _meta from function_invocation_kwargs to MCP …

python/packages/core/agent_framework/_mcp.py

@@ -1076,12 +1076,17 @@ async def call_tool(self, tool_name: str, **kwargs: Any) -> str | list[Content]:
             raise ToolExecutionException(
                 "Tools are not loaded for this server, please set load_tools=True in the constructor."
             )
+        # Extract user-supplied _meta before filtering so it is forwarded as
+        # MCP request metadata rather than as a tool argument.
+        user_meta = kwargs.pop("_meta", None)
+
         # Filter out framework kwargs that cannot be serialized by the MCP SDK.
         # These are internal objects passed through the function invocation pipeline
         # that should not be forwarded to external MCP servers.
         # conversation_id is an internal tracking ID used by services like Azure AI.
         # options contains metadata/store used by AG-UI for Azure AI client requirements.
         # response_format is a Pydantic model class used for structured output (not serializable).
+        # _meta is handled separately and merged into the MCP request meta field.
         filtered_kwargs = {
             k: v
             for k, v in kwargs.items()
@@ -1095,11 +1100,13 @@ async def call_tool(self, tool_name: str, **kwargs: Any) -> str | list[Content]:
                 "conversation_id",
                 "options",
                 "response_format",
+                "_meta",
             }
         }
 
-        # Inject OpenTelemetry trace context into MCP _meta for distributed tracing.
-        otel_meta = _inject_otel_into_mcp_meta()
+        # Merge user-supplied _meta with OpenTelemetry trace context.
+        # User keys take precedence; OTel keys fill in non-conflicting slots.
+        otel_meta = _inject_otel_into_mcp_meta(dict(user_meta) if user_meta else None)
 
         parser = self.parse_tool_results or self._parse_tool_result_from_mcp
         # Try the operation, reconnecting once if the connection is closed