Update app.py

app.py

@@ -277,7 +277,7 @@ def chat(message, history):
             tool_outputs=[
                 {
                     "tool_call_id": tool_call_ids[0],
-                    "output": tool_call_results[0].to_json()
+                    "output": tool_call_results[0]
                 }
             ]
         )