Skip empty SSE data to avoid parsing errors

Author: felixweinberger

examples/clients/simple-task-client/mcp_simple_task_client/main.py

@@ -33,8 +33,8 @@ async def run(url: str) -> None:
                 ClientRequest(
                     CallToolRequest(
                         params=CallToolRequestParams(
-                            name="long_running_task",
-                            arguments={},
+                            name="delay",
+                            arguments={"duration": 3000},
                             task=TaskMetadata(ttl=60000),
                         )
                     )

src/mcp/client/streamable_http.py

@@ -160,6 +160,9 @@ async def _handle_sse_event(
     ) -> bool:
         """Handle an SSE event, returning True if the response is complete."""
         if sse.event == "message":
+            # Skip empty data (keep-alive pings)
+            if not sse.data:
+                return False
             try:
                 message = JSONRPCMessage.model_validate_json(sse.data)
                 logger.debug(f"SSE message: {message}")