Fix weather agent example with UI (#1851)

Co-authored-by: Varnavas <vp@localhost>

Author: vp777

examples/pydantic_ai_examples/weather_agent_gradio.py

@@ -33,16 +33,12 @@ async def stream_from_agent(prompt: str, chatbot: list[dict], past_messages: lis
         for message in result.new_messages():
             for call in message.parts:
                 if isinstance(call, ToolCallPart):
-                    call_args = (
-                        call.args.args_json
-                        if hasattr(call.args, 'args_json')
-                        else json.dumps(call.args.args_dict)
-                    )
+                    call_args = call.args_as_json_str()
                     metadata = {
                         'title': f'🛠️ Using {TOOL_TO_DISPLAY_NAME[call.tool_name]}',
                     }
                     if call.tool_call_id is not None:
-                        metadata['id'] = {call.tool_call_id}
+                        metadata['id'] = call.tool_call_id
 
                     gr_message = {
                         'role': 'assistant',