Fix AssistantAgent Tool Call Behavior

python/packages/autogen-agentchat/src/autogen_agentchat/agents/_assistant_agent.py

@@ -50,11 +50,42 @@ def model_post_init(self, __context: Any) -> None:
 class AssistantAgent(BaseChatAgent):
     """An agent that provides assistance with tool use.
 
-    ```{note}
-    The assistant agent is not thread-safe or coroutine-safe.
-    It should not be shared between multiple tasks or coroutines, and it should
-    not call its methods concurrently.
-    ```
+    The :meth:`on_messages` returns a :class:`~autogen_agentchat.base.Response`
+    in which :attr:`~autogen_agentchat.base.Response.chat_message` is the final
+    response message.
+
+    The :meth:`on_messages_stream` creates an async generator that produces
+    the inner messages as they are created, and the :class:`~autogen_agentchat.base.Response`
+    object as the last item before closing the generator.
+
+    Tool call behavior:
+
+    * If the model returns no tool call, then the response is immediately returned as a :class:`~autogen_agentchat.messages.TextMessage` in :attr:`~autogen_agentchat.base.Response.chat_message`.
+    * When the model returns tool calls, they will be executed right away:
+        - When `reflect_on_tool_use` is False (default), the tool call results are returned as a :class:`~autogen_agentchat.messages.TextMessage` in :attr:`~autogen_agentchat.base.Response.chat_message`. `tool_call_summary_format` can be used to customize the tool call summary.
+        - When `reflect_on_tool_use` is True, the another model inference is made using the tool calls and results, and the text response is returned as a :class:`~autogen_agentchat.messages.TextMessage` in :attr:`~autogen_agentchat.base.Response.chat_message`.
+
+    Hand off behavior:
+
+    * If a handoff is triggered, a :class:`~autogen_agentchat.messages.HandoffMessage` will be returned in :attr:`~autogen_agentchat.base.Response.chat_message`.
+    * If there are tool calls, they will also be executed right away before returning the handoff.
+
+
+    .. note::
+        The assistant agent is not thread-safe or coroutine-safe.
+        It should not be shared between multiple tasks or coroutines, and it should
+        not call its methods concurrently.
+
+    .. note::
+        By default, the tool call results are returned as response when tool calls are made.
+        So it is recommended to pay attention to the formatting of the tools return values,
+        especially if another agent is expecting them in a specific format.
+        Use `tool_call_summary_format` to customize the tool call summary, if needed.
+
+    .. note::
+        If multiple handoffs are detected, only the first handoff is executed.
+
+
 
     Args:
         name (str): The name of the agent.
@@ -66,11 +97,20 @@ class AssistantAgent(BaseChatAgent):
             If a handoff is a string, it should represent the target agent's name.
         description (str, optional): The description of the agent.
         system_message (str, optional): The system message for the model.
+        reflect_on_tool_use (bool, optional): If `True`, the agent will make another model inference using the tool call and result
+            to generate a response. If `False`, the tool call result will be returned as the response. Defaults to `False`.
+        tool_call_summary_format (str, optional): The format string used to create a tool call summary for every tool call result.
+            Defaults to "{result}".
+            When `reflect_on_tool_use` is `False`, a concatenation of all the tool call summaries, separated by a new line character ('\\n')
+            will be returned as the response.
+            Available variables: `{tool_name}`, `{arguments}`, `{result}`.
+            For example, `"{tool_name}: {result}"` will create a summary like `"tool_name: result"`.
 
     Raises:
         ValueError: If tool names are not unique.
         ValueError: If handoff names are not unique.
         ValueError: If handoff names are not unique from tool names.
+        ValueError: If maximum number of tool iterations is less than 1.
 
     Examples:
 
@@ -181,6 +221,8 @@ def __init__(
         description: str = "An agent that provides assistance with ability to use tools.",
         system_message: str
         | None = "You are a helpful AI assistant. Solve tasks using your tools. Reply with TERMINATE when the task has been completed.",
+        reflect_on_tool_use: bool = False,
+        tool_call_summary_format: str = "{result}",
     ):
         super().__init__(name=name, description=description)
         self._model_client = model_client
@@ -231,6 +273,8 @@ def __init__(
                 f"Handoff names must be unique from tool names. Handoff names: {handoff_tool_names}; tool names: {tool_names}"
             )
         self._model_context: List[LLMMessage] = []
+        self._reflect_on_tool_use = reflect_on_tool_use
+        self._tool_call_summary_format = tool_call_summary_format
         self._is_running = False
 
     @property
@@ -267,53 +311,77 @@ async def on_messages_stream(
         # Add the response to the model context.
         self._model_context.append(AssistantMessage(content=result.content, source=self.name))
 
-        # Run tool calls until the model produces a string response.
-        while isinstance(result.content, list) and all(isinstance(item, FunctionCall) for item in result.content):
-            tool_call_msg = ToolCallMessage(content=result.content, source=self.name, models_usage=result.usage)
-            event_logger.debug(tool_call_msg)
-            # Add the tool call message to the output.
-            inner_messages.append(tool_call_msg)
-            yield tool_call_msg
-
-            # Execute the tool calls.
-            results = await asyncio.gather(
-                *[self._execute_tool_call(call, cancellation_token) for call in result.content]
+        # Check if the response is a string and return it.
+        if isinstance(result.content, str):
+            yield Response(
+                chat_message=TextMessage(content=result.content, source=self.name, models_usage=result.usage),
+                inner_messages=inner_messages,
             )
-            tool_call_result_msg = ToolCallResultMessage(content=results, source=self.name)
-            event_logger.debug(tool_call_result_msg)
-            self._model_context.append(FunctionExecutionResultMessage(content=results))
-            inner_messages.append(tool_call_result_msg)
-            yield tool_call_result_msg
-
-            # Detect handoff requests.
-            handoffs: List[HandoffBase] = []
-            for call in result.content:
-                if call.name in self._handoffs:
-                    handoffs.append(self._handoffs[call.name])
-            if len(handoffs) > 0:
-                if len(handoffs) > 1:
-                    raise ValueError(f"Multiple handoffs detected: {[handoff.name for handoff in handoffs]}")
-                # Return the output messages to signal the handoff.
-                yield Response(
-                    chat_message=HandoffMessage(
-                        content=handoffs[0].message, target=handoffs[0].target, source=self.name
-                    ),
-                    inner_messages=inner_messages,
+            return
+
+        # Process tool calls.
+        assert isinstance(result.content, list) and all(isinstance(item, FunctionCall) for item in result.content)
+        tool_call_msg = ToolCallMessage(content=result.content, source=self.name, models_usage=result.usage)
+        event_logger.debug(tool_call_msg)
+        # Add the tool call message to the output.
+        inner_messages.append(tool_call_msg)
+        yield tool_call_msg
+
+        # Execute the tool calls.
+        results = await asyncio.gather(*[self._execute_tool_call(call, cancellation_token) for call in result.content])
+        tool_call_result_msg = ToolCallResultMessage(content=results, source=self.name)
+        event_logger.debug(tool_call_result_msg)
+        self._model_context.append(FunctionExecutionResultMessage(content=results))
+        inner_messages.append(tool_call_result_msg)
+        yield tool_call_result_msg
+
+        # Detect handoff requests.
+        handoffs: List[HandoffBase] = []
+        for call in result.content:
+            if call.name in self._handoffs:
+                handoffs.append(self._handoffs[call.name])
+        if len(handoffs) > 0:
+            if len(handoffs) > 1:
+                # show warning if multiple handoffs detected
+                warnings.warn(
+                    f"Multiple handoffs detected only the first is executed: {[handoff.name for handoff in handoffs]}",
+                    stacklevel=2,
                 )
-                return
+            # Return the output messages to signal the handoff.
+            yield Response(
+                chat_message=HandoffMessage(content=handoffs[0].message, target=handoffs[0].target, source=self.name),
+                inner_messages=inner_messages,
+            )
+            return
 
-            # Generate an inference result based on the current model context.
+        if self._reflect_on_tool_use:
+            # Generate another inference result based on the tool call and result.
             llm_messages = self._system_messages + self._model_context
-            result = await self._model_client.create(
-                llm_messages, tools=self._tools + self._handoff_tools, cancellation_token=cancellation_token
-            )
+            result = await self._model_client.create(llm_messages, cancellation_token=cancellation_token)
+            assert isinstance(result.content, str)
+            # Add the response to the model context.
             self._model_context.append(AssistantMessage(content=result.content, source=self.name))
-
-        assert isinstance(result.content, str)
-        yield Response(
-            chat_message=TextMessage(content=result.content, source=self.name, models_usage=result.usage),
-            inner_messages=inner_messages,
-        )
+            # Yield the response.
+            yield Response(
+                chat_message=TextMessage(content=result.content, source=self.name, models_usage=result.usage),
+                inner_messages=inner_messages,
+            )
+        else:
+            # Return tool call result as the response.
+            tool_call_summaries: List[str] = []
+            for i in range(len(tool_call_msg.content)):
+                tool_call_summaries.append(
+                    self._tool_call_summary_format.format(
+                        tool_name=tool_call_msg.content[i].name,
+                        arguments=tool_call_msg.content[i].arguments,
+                        result=tool_call_result_msg.content[i].content,
+                    ),
+                )
+            tool_call_summary = "\n".join(tool_call_summaries)
+            yield Response(
+                chat_message=TextMessage(content=tool_call_summary, source=self.name),
+                inner_messages=inner_messages,
+            )
 
     async def _execute_tool_call(
         self, tool_call: FunctionCall, cancellation_token: CancellationToken

python/packages/autogen-agentchat/tests/test_assistant_agent.py

@@ -118,6 +118,106 @@ async def test_run_with_tools(monkeypatch: pytest.MonkeyPatch) -> None:
         tools=[_pass_function, _fail_function, FunctionTool(_echo_function, description="Echo")],
     )
     result = await agent.run(task="task")
+
+    assert len(result.messages) == 4
+    assert isinstance(result.messages[0], TextMessage)
+    assert result.messages[0].models_usage is None
+    assert isinstance(result.messages[1], ToolCallMessage)
+    assert result.messages[1].models_usage is not None
+    assert result.messages[1].models_usage.completion_tokens == 5
+    assert result.messages[1].models_usage.prompt_tokens == 10
+    assert isinstance(result.messages[2], ToolCallResultMessage)
+    assert result.messages[2].models_usage is None
+    assert isinstance(result.messages[3], TextMessage)
+    assert result.messages[3].content == "pass"
+    assert result.messages[3].models_usage is None
+
+    # Test streaming.
+    mock._curr_index = 0  # pyright: ignore
+    index = 0
+    async for message in agent.run_stream(task="task"):
+        if isinstance(message, TaskResult):
+            assert message == result
+        else:
+            assert message == result.messages[index]
+        index += 1
+
+    # Test state saving and loading.
+    state = await agent.save_state()
+    agent2 = AssistantAgent(
+        "tool_use_agent",
+        model_client=OpenAIChatCompletionClient(model=model, api_key=""),
+        tools=[_pass_function, _fail_function, FunctionTool(_echo_function, description="Echo")],
+    )
+    await agent2.load_state(state)
+    state2 = await agent2.save_state()
+    assert state == state2
+
+
+@pytest.mark.asyncio
+async def test_run_with_tools_and_reflection(monkeypatch: pytest.MonkeyPatch) -> None:
+    model = "gpt-4o-2024-05-13"
+    chat_completions = [
+        ChatCompletion(
+            id="id1",
+            choices=[
+                Choice(
+                    finish_reason="tool_calls",
+                    index=0,
+                    message=ChatCompletionMessage(
+                        content=None,
+                        tool_calls=[
+                            ChatCompletionMessageToolCall(
+                                id="1",
+                                type="function",
+                                function=Function(
+                                    name="_pass_function",
+                                    arguments=json.dumps({"input": "task"}),
+                                ),
+                            )
+                        ],
+                        role="assistant",
+                    ),
+                )
+            ],
+            created=0,
+            model=model,
+            object="chat.completion",
+            usage=CompletionUsage(prompt_tokens=10, completion_tokens=5, total_tokens=0),
+        ),
+        ChatCompletion(
+            id="id2",
+            choices=[
+                Choice(finish_reason="stop", index=0, message=ChatCompletionMessage(content="Hello", role="assistant"))
+            ],
+            created=0,
+            model=model,
+            object="chat.completion",
+            usage=CompletionUsage(prompt_tokens=10, completion_tokens=5, total_tokens=0),
+        ),
+        ChatCompletion(
+            id="id2",
+            choices=[
+                Choice(
+                    finish_reason="stop", index=0, message=ChatCompletionMessage(content="TERMINATE", role="assistant")
+                )
+            ],
+            created=0,
+            model=model,
+            object="chat.completion",
+            usage=CompletionUsage(prompt_tokens=10, completion_tokens=5, total_tokens=0),
+        ),
+    ]
+    mock = _MockChatCompletion(chat_completions)
+    monkeypatch.setattr(AsyncCompletions, "create", mock.mock_create)
+    agent = AssistantAgent(
+        "tool_use_agent",
+        model_client=OpenAIChatCompletionClient(model=model, api_key=""),
+        tools=[_pass_function, _fail_function, FunctionTool(_echo_function, description="Echo")],
+        reflect_on_tool_use=True,
+    )
+    result = await agent.run(task="task")
+
     assert len(result.messages) == 4
     assert isinstance(result.messages[0], TextMessage)
     assert result.messages[0].models_usage is None
@@ -128,6 +228,7 @@ async def test_run_with_tools(monkeypatch: pytest.MonkeyPatch) -> None:
     assert isinstance(result.messages[2], ToolCallResultMessage)
     assert result.messages[2].models_usage is None
     assert isinstance(result.messages[3], TextMessage)
+    assert result.messages[3].content == "Hello"
     assert result.messages[3].models_usage is not None
     assert result.messages[3].models_usage.completion_tokens == 5
     assert result.messages[3].models_usage.prompt_tokens == 10

python/packages/autogen-agentchat/tests/test_group_chat.py

@@ -32,8 +32,7 @@
 from autogen_agentchat.teams._group_chat._selector_group_chat import SelectorGroupChatManager
 from autogen_agentchat.teams._group_chat._swarm_group_chat import SwarmGroupChatManager
 from autogen_agentchat.ui import Console
-from autogen_core import AgentId, CancellationToken, FunctionCall
-from autogen_core.models import FunctionExecutionResult
+from autogen_core import AgentId, CancellationToken
 from autogen_core.tools import FunctionTool
 from autogen_ext.code_executors.local import LocalCommandLineCodeExecutor
 from autogen_ext.models import OpenAIChatCompletionClient, ReplayChatCompletionClient
@@ -306,6 +305,7 @@ async def test_round_robin_group_chat_with_tools(monkeypatch: pytest.MonkeyPatch
             usage=CompletionUsage(prompt_tokens=0, completion_tokens=0, total_tokens=0),
         ),
     ]
+    # Test with repeat tool calls once
     mock = _MockChatCompletion(chat_completions)
     monkeypatch.setattr(AsyncCompletions, "create", mock.mock_create)
     tool = FunctionTool(_pass_function, name="pass", description="pass function")
@@ -320,27 +320,18 @@ async def test_round_robin_group_chat_with_tools(monkeypatch: pytest.MonkeyPatch
     result = await team.run(
         task="Write a program that prints 'Hello, world!'",
     )
-
-    assert len(result.messages) == 6
+    assert len(result.messages) == 8
     assert isinstance(result.messages[0], TextMessage)  # task
     assert isinstance(result.messages[1], ToolCallMessage)  # tool call
     assert isinstance(result.messages[2], ToolCallResultMessage)  # tool call result
     assert isinstance(result.messages[3], TextMessage)  # tool use agent response
     assert isinstance(result.messages[4], TextMessage)  # echo agent response
     assert isinstance(result.messages[5], TextMessage)  # tool use agent response
-    assert result.stop_reason is not None and result.stop_reason == "Text 'TERMINATE' mentioned"
+    assert isinstance(result.messages[6], TextMessage)  # echo agent response
+    assert isinstance(result.messages[7], TextMessage)  # tool use agent response, that has TERMINATE
+    assert result.messages[7].content == "TERMINATE"
 
-    context = tool_use_agent._model_context  # pyright: ignore
-    assert context[0].content == "Write a program that prints 'Hello, world!'"
-    assert isinstance(context[1].content, list)
-    assert isinstance(context[1].content[0], FunctionCall)
-    assert context[1].content[0].name == "pass"
-    assert context[1].content[0].arguments == json.dumps({"input": "pass"})
-    assert isinstance(context[2].content, list)
-    assert isinstance(context[2].content[0], FunctionExecutionResult)
-    assert context[2].content[0].content == "pass"
-    assert context[2].content[0].call_id == "1"
-    assert context[3].content == "Hello"
+    assert result.stop_reason is not None and result.stop_reason == "Text 'TERMINATE' mentioned"
 
     # Test streaming.
     tool_use_agent._model_context.clear()  # pyright: ignore