ToolNode是一个 LangChain Runnable，它将图形状态（带有消息列表）作为输入，并使用工具调用的结果输出状态更新。注意ToolNode是通过AIMessage的tool_calls字段绑定

@tool
def query_by_tag_and_question(question: str, tag: str):
    """根据问题和标签查询相关信息"""
    print("query_by_tag_and_question被调用")
    if tag == "复变函数" and question == "示例问题":
        return "查询到的相关信息"
    return "什么内容都没有查询到"

tool_node = ToolNode(tools=[query_by_tag_and_question])

message_with_tool_calls = AIMessage(
    content="What is the derivative of a function?",
    tool_calls=[
        {
           "name": "query_by_tag_and_question",
           "args": {
                "question": "猜猜我要什么内容",
                "tag": "复变函数"
            },
            "id": "tool_call_id_1",
            "type":"tool_call"
        }
    ]
)
result = tool_node.invoke({"messages": [message_with_tool_calls]})
print("预期不命中")
print(result["messages"][-1].content)
print("---------------------------------------------------------")


message_with_tool_calls = AIMessage(
    content="What is the derivative of a function?",
    tool_calls=[
        {
           "name": "query_by_tag_and_question",
            "args": {
                "question": "示例问题",
                "tag": "复变函数"
            },
            "id": "tool_call_id_1",
            "type":"tool_call"
        }
    ]
)

result = tool_node.invoke({"messages": [message_with_tool_calls]})
print("预期命中")
print(result["messages"][-1].content)
print("---------------------------------------------------------")

query_by_tag_and_question被调用
预期不命中
什么内容都没有查询到
---------------------------------------------------------
query_by_tag_and_question被调用
预期命中
查询到的相关信息
---------------------------------------------------------

@tool
def get_weather(location: str):
    """Call to get the current weather."""
    if location.lower() in ["sf", "san francisco"]:
        return "大雾"
    else:
        return "阳光明媚"


@tool
def get_coolest_cities():
    """Get a list of coolest cities"""
    return "nyc, sf"


tools = [get_weather, get_coolest_cities]
tool_node = ToolNode(tools)

message_with_multiple_tool_calls = AIMessage(
    content="",
    tool_calls=[
        {
            "name": "get_coolest_cities",
            "args": {},
            "id": "tool_call_id_2",
            "type": "tool_call",
        },
        {
            "name": "get_weather",
            "args": {"location": "sf"},
            "id": "tool_call_id_1",
            "type": "tool_call",
        },
    ],
)

result=tool_node.invoke({"messages": [message_with_multiple_tool_calls]})
for m in result["messages"]:
    print(f"{m.tool_call_id}: {m.content}")

tool_call_id_2: nyc, sf
tool_call_id_1: 大雾