chore: AsyncAgent should use ToolResponse instead of ToolResponseMessage (#197)

Summary:

Test Plan:
test with script in:
https://github.com/meta-llama/llama-stack-apps/blob/async_agent/examples/agents/async_agent.py

Author: ehhuang

src/llama_stack_client/lib/agents/agent.py

@@ -439,7 +439,7 @@ async def create_turn(
                 raise Exception("Turn did not complete")
             return chunks[-1].event.payload.turn
 
-    async def _run_tool(self, tool_calls: List[ToolCall]) -> ToolResponseMessage:
+    async def _run_tool(self, tool_calls: List[ToolCall]) -> ToolResponseParam:
         assert len(tool_calls) == 1, "Only one tool call is supported"
         tool_call = tool_calls[0]
 
@@ -464,20 +464,18 @@ async def _run_tool(self, tool_calls: List[ToolCall]) -> ToolResponseMessage:
                 tool_name=tool_call.tool_name,
                 kwargs=tool_call.arguments,
             )
-            tool_response_message = ToolResponseMessage(
+            tool_response = ToolResponseParam(
                 call_id=tool_call.call_id,
                 tool_name=tool_call.tool_name,
                 content=tool_result.content,
-                role="tool",
             )
-            return tool_response_message
+            return tool_response
 
         # cannot find tools
-        return ToolResponseMessage(
+        return ToolResponseParam(
             call_id=tool_call.call_id,
             tool_name=tool_call.tool_name,
             content=f"Unknown tool `{tool_call.tool_name}` was called.",
-            role="tool",
         )
 
     async def _create_turn_streaming(
@@ -524,14 +522,14 @@ async def _create_turn_streaming(
                         yield chunk
 
                     # run the tools
-                    tool_response_message = await self._run_tool(tool_calls)
+                    tool_response = await self._run_tool(tool_calls)
 
                     # pass it to next iteration
                     turn_response = await self.client.agents.turn.resume(
                         agent_id=self.agent_id,
                         session_id=session_id or self.session_id[-1],
                         turn_id=turn_id,
-                        tool_responses=[tool_response_message],
+                        tool_responses=[tool_response],
                         stream=True,
                     )
                     n_iter += 1