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多智能体主管

主管是一种多智能体架构，其中由一个中央主管智能体协调专业的智能体。主管智能体控制所有通信流和任务委派，根据当前上下文和任务要求决定调用哪个智能体。

在本教程中，您将构建一个包含两个智能体（研究智能体和数学智能体）的主管系统。在本教程结束时，您将能够

  1. 构建专业的研究智能体和数学智能体
  2. 使用预构建的 langgraph-supervisor 构建一个主管来协调它们
  3. 从头构建一个主管
  4. 实现高级任务委派

diagram

设置

首先，让我们安装所需的包并设置我们的 API 密钥

pip install -U langgraph langgraph-supervisor langchain-tavily "langchain[openai]"

import getpass
import os


def _set_if_undefined(var: str):
    if not os.environ.get(var):
        os.environ[var] = getpass.getpass(f"Please provide your {var}")


_set_if_undefined("OPENAI_API_KEY")
_set_if_undefined("TAVILY_API_KEY")

设置 LangSmith 以进行 LangGraph 开发

注册 LangSmith 以快速发现问题并提高 LangGraph 项目的性能。LangSmith 允许您使用跟踪数据调试、测试和监控您使用 LangGraph 构建的 LLM 应用程序 — 在此处阅读更多关于如何入门的信息。

1. 创建工作智能体

首先，让我们创建我们的专业工作智能体 — 研究智能体和数学智能体

  • 研究智能体将使用 Tavily API 访问一个网络搜索工具
  • 数学智能体将访问简单的数学工具（add, multiply, divide）

研究智能体

对于网络搜索，我们将使用来自 langchain-tavily 的 TavilySearch 工具

API 参考: TavilySearch

from langchain_tavily import TavilySearch

web_search = TavilySearch(max_results=3)
web_search_results = web_search.invoke("who is the mayor of NYC?")

print(web_search_results["results"][0]["content"])

Mayor Eric Adams has served the people of New York City as an NYPD officer, State Senator, Brooklyn Borough President, and now as the 110th Mayor of the City of New York. He gave voice to a diverse coalition of working families in all five boroughs and is leading the fight to bring back New York City’s economy, reduce inequality, improve public safety, and build a stronger, healthier city that delivers for all New Yorkers. Mayor Eric Adams has served the people of New York City as an NYPD officer, State Senator, Brooklyn Borough President, and now as the 110th Mayor of the City of New York. NYC is a trademark and service mark of the City of New York.
要创建单个工作智能体，我们将使用 LangGraph 的预构建智能体。

API 参考: create_react_agent

from langgraph.prebuilt import create_react_agent

research_agent = create_react_agent(
    model="openai:gpt-4.1",
    tools=[web_search],
    prompt=(
        "You are a research agent.\n\n"
        "INSTRUCTIONS:\n"
        "- Assist ONLY with research-related tasks, DO NOT do any math\n"
        "- After you're done with your tasks, respond to the supervisor directly\n"
        "- Respond ONLY with the results of your work, do NOT include ANY other text."
    ),
    name="research_agent",
)

让我们运行智能体来验证它的行为是否符合预期。

我们将使用 pretty_print_messages 辅助函数来美观地渲染流式智能体输出 
from langchain_core.messages import convert_to_messages


def pretty_print_message(message, indent=False):
    pretty_message = message.pretty_repr(html=True)
    if not indent:
        print(pretty_message)
        return

    indented = "\n".join("\t" + c for c in pretty_message.split("\n"))
    print(indented)


def pretty_print_messages(update, last_message=False):
    is_subgraph = False
    if isinstance(update, tuple):
        ns, update = update
        # skip parent graph updates in the printouts
        if len(ns) == 0:
            return

        graph_id = ns[-1].split(":")[0]
        print(f"Update from subgraph {graph_id}:")
        print("\n")
        is_subgraph = True

    for node_name, node_update in update.items():
        update_label = f"Update from node {node_name}:"
        if is_subgraph:
            update_label = "\t" + update_label

        print(update_label)
        print("\n")

        messages = convert_to_messages(node_update["messages"])
        if last_message:
            messages = messages[-1:]

        for m in messages:
            pretty_print_message(m, indent=is_subgraph)
        print("\n")


for chunk in research_agent.stream(
    {"messages": [{"role": "user", "content": "who is the mayor of NYC?"}]}
):
    pretty_print_messages(chunk)

Update from node agent:


================================== Ai Message ==================================
Name: research_agent
Tool Calls:
  tavily_search (call_T4wrj7DKAG5hVtNVhjRYGdei)
 Call ID: call_T4wrj7DKAG5hVtNVhjRYGdei
  Args:
    query: current mayor of New York City


Update from node tools:


================================= Tool Message =================================
Name: tavily_search

{"query": "current mayor of New York City", "follow_up_questions": null, "answer": null, "images": [], "results": [{"title": "List of mayors of New York City - Wikipedia", "url": "https://en.wikipedia.org/wiki/List_of_mayors_of_New_York_City", "content": "The mayor of New York City is the chief executive of the Government of New York City, as stipulated by New York City's charter.The current officeholder, the 110th in the sequence of regular mayors, is Eric Adams, a member of the Democratic Party.. During the Dutch colonial period from 1624 to 1664, New Amsterdam was governed by the Director of New Netherland.", "score": 0.9039154, "raw_content": null}, {"title": "Office of the Mayor | Mayor's Bio | City of New York - NYC.gov", "url": "https://www.nyc.gov/office-of-the-mayor/bio.page", "content": "Mayor Eric Adams has served the people of New York City as an NYPD officer, State Senator, Brooklyn Borough President, and now as the 110th Mayor of the City of New York. He gave voice to a diverse coalition of working families in all five boroughs and is leading the fight to bring back New York City's economy, reduce inequality, improve", "score": 0.8405867, "raw_content": null}, {"title": "Eric Adams - Wikipedia", "url": "https://en.wikipedia.org/wiki/Eric_Adams", "content": "Eric Leroy Adams (born September 1, 1960) is an American politician and former police officer who has served as the 110th mayor of New York City since 2022. Adams was an officer in the New York City Transit Police and then the New York City Police Department (NYPD) for more than 20 years, retiring at the rank of captain.He served in the New York State Senate from 2006 to 2013, representing the", "score": 0.77731717, "raw_content": null}], "response_time": 1.31}


Update from node agent:


================================== Ai Message ==================================
Name: research_agent

The current mayor of New York City is Eric Adams.

数学智能体

对于数学智能体工具，我们将使用普通的 Python 函数

def add(a: float, b: float):
    """Add two numbers."""
    return a + b


def multiply(a: float, b: float):
    """Multiply two numbers."""
    return a * b


def divide(a: float, b: float):
    """Divide two numbers."""
    return a / b


math_agent = create_react_agent(
    model="openai:gpt-4.1",
    tools=[add, multiply, divide],
    prompt=(
        "You are a math agent.\n\n"
        "INSTRUCTIONS:\n"
        "- Assist ONLY with math-related tasks\n"
        "- After you're done with your tasks, respond to the supervisor directly\n"
        "- Respond ONLY with the results of your work, do NOT include ANY other text."
    ),
    name="math_agent",
)

让我们运行数学智能体

for chunk in math_agent.stream(
    {"messages": [{"role": "user", "content": "what's (3 + 5) x 7"}]}
):
    pretty_print_messages(chunk)

Update from node agent:


================================== Ai Message ==================================
Name: math_agent
Tool Calls:
  add (call_LqyOrR1Ktr2LVLDlXpbWNAsp)
 Call ID: call_LqyOrR1Ktr2LVLDlXpbWNAsp
  Args:
    a: 3
    b: 5


Update from node tools:


================================= Tool Message =================================
Name: add

8.0


Update from node agent:


================================== Ai Message ==================================
Name: math_agent
Tool Calls:
  multiply (call_IBXYtlEMdZrfDZ8g8bWC31pM)
 Call ID: call_IBXYtlEMdZrfDZ8g8bWC31pM
  Args:
    a: 8
    b: 7


Update from node tools:


================================= Tool Message =================================
Name: multiply

56.0


Update from node agent:


================================== Ai Message ==================================
Name: math_agent

56

2. 使用 langgraph-supervisor 创建主管

为了实现我们的多智能体系统，我们将使用预构建的 langgraph-supervisor 库中的 create_supervisor

API 参考: create_supervisor | init_chat_model

from langgraph_supervisor import create_supervisor
from langchain.chat_models import init_chat_model

supervisor = create_supervisor(
    model=init_chat_model("openai:gpt-4.1"),
    agents=[research_agent, math_agent],
    prompt=(
        "You are a supervisor managing two agents:\n"
        "- a research agent. Assign research-related tasks to this agent\n"
        "- a math agent. Assign math-related tasks to this agent\n"
        "Assign work to one agent at a time, do not call agents in parallel.\n"
        "Do not do any work yourself."
    ),
    add_handoff_back_messages=True,
    output_mode="full_history",
).compile()

from IPython.display import display, Image

display(Image(supervisor.get_graph().draw_mermaid_png()))

现在让我们使用一个需要两个智能体的查询来运行它

  • 研究智能体将查找必要的 GDP 信息
  • 数学智能体将执行除法以找到纽约州 GDP 的百分比，就像要求的那样

for chunk in supervisor.stream(
    {
        "messages": [
            {
                "role": "user",
                "content": "find US and New York state GDP in 2024. what % of US GDP was New York state?",
            }
        ]
    },
):
    pretty_print_messages(chunk, last_message=True)

final_message_history = chunk["supervisor"]["messages"]

Update from node supervisor:


================================= Tool Message =================================
Name: transfer_to_research_agent

Successfully transferred to research_agent


Update from node research_agent:


================================= Tool Message =================================
Name: transfer_back_to_supervisor

Successfully transferred back to supervisor


Update from node supervisor:


================================= Tool Message =================================
Name: transfer_to_math_agent

Successfully transferred to math_agent


Update from node math_agent:


================================= Tool Message =================================
Name: transfer_back_to_supervisor

Successfully transferred back to supervisor


Update from node supervisor:


================================== Ai Message ==================================
Name: supervisor

The US GDP in 2024 was $29.017 trillion, and New York State's GDP was $2.284 trillion. New York State accounted for approximately 7.87% of the total US GDP in 2024.

3. 从头创建主管

现在让我们从头实现这个相同的多智能体系统。我们将需要

  1. 设置主管如何与单个智能体通信
  2. 创建主管智能体
  3. 将主管和工作智能体组合成一个单一的多智能体图。

设置智能体通信

我们需要定义一种主管智能体与工作智能体通信的方式。在多智能体架构中实现这一点的常见方式是使用交接（handoffs），即一个智能体将控制权交接（hands off）给另一个智能体。交接允许您指定

  • destination: 要移交到的目标智能体
  • payload: 要传递给该智能体的信息

我们将通过交接工具（handoff tools）实现交接，并将这些工具提供给主管智能体：当主管调用这些工具时，它会将控制权交给一个工作智能体，并将完整的消息历史记录传递给该智能体。

API 参考: tool | InjectedToolCallId | InjectedState | StateGraph | START | Command

from typing import Annotated
from langchain_core.tools import tool, InjectedToolCallId
from langgraph.prebuilt import InjectedState
from langgraph.graph import StateGraph, START, MessagesState
from langgraph.types import Command


def create_handoff_tool(*, agent_name: str, description: str | None = None):
    name = f"transfer_to_{agent_name}"
    description = description or f"Ask {agent_name} for help."

    @tool(name, description=description)
    def handoff_tool(
        state: Annotated[MessagesState, InjectedState],
        tool_call_id: Annotated[str, InjectedToolCallId],
    ) -> Command:
        tool_message = {
            "role": "tool",
            "content": f"Successfully transferred to {agent_name}",
            "name": name,
            "tool_call_id": tool_call_id,
        }
        return Command(
            goto=agent_name,  # (1)!
            update={**state, "messages": state["messages"] + [tool_message]},  # (2)!
            graph=Command.PARENT,  # (3)!
        )

    return handoff_tool


# Handoffs
assign_to_research_agent = create_handoff_tool(
    agent_name="research_agent",
    description="Assign task to a researcher agent.",
)

assign_to_math_agent = create_handoff_tool(
    agent_name="math_agent",
    description="Assign task to a math agent.",
)
  1. 要交接到的智能体或节点的名称。
  2. 获取智能体的消息并将它们作为交接的一部分添加到父状态中。下一个智能体将看到父状态。
  3. 指示 LangGraph 我们需要在父级多智能体图中导航到智能体节点。

创建主管智能体

然后，让我们使用刚刚定义的交接工具创建主管智能体。我们将使用预构建的 create_react_agent

supervisor_agent = create_react_agent(
    model="openai:gpt-4.1",
    tools=[assign_to_research_agent, assign_to_math_agent],
    prompt=(
        "You are a supervisor managing two agents:\n"
        "- a research agent. Assign research-related tasks to this agent\n"
        "- a math agent. Assign math-related tasks to this agent\n"
        "Assign work to one agent at a time, do not call agents in parallel.\n"
        "Do not do any work yourself."
    ),
    name="supervisor",
)

创建多智能体图

将所有这些放在一起，让我们为我们的整体多智能体系统创建一个图。我们将把主管和单个智能体添加为子图节点。

API 参考: END

from langgraph.graph import END

# Define the multi-agent supervisor graph
supervisor = (
    StateGraph(MessagesState)
    # NOTE: `destinations` is only needed for visualization and doesn't affect runtime behavior
    .add_node(supervisor_agent, destinations=("research_agent", "math_agent", END))
    .add_node(research_agent)
    .add_node(math_agent)
    .add_edge(START, "supervisor")
    # always return back to the supervisor
    .add_edge("research_agent", "supervisor")
    .add_edge("math_agent", "supervisor")
    .compile()
)

注意，我们添加了从工作智能体回到主管的显式边 — 这意味着它们保证将控制权返回给主管。如果您希望智能体直接响应用户（即，将系统变成一个路由器），您可以移除这些边。

from IPython.display import display, Image

display(Image(supervisor.get_graph().draw_mermaid_png()))

创建好多智能体图后，现在让我们来运行它！

for chunk in supervisor.stream(
    {
        "messages": [
            {
                "role": "user",
                "content": "find US and New York state GDP in 2024. what % of US GDP was New York state?",
            }
        ]
    },
):
    pretty_print_messages(chunk, last_message=True)

final_message_history = chunk["supervisor"]["messages"]

Update from node supervisor:


================================= Tool Message =================================
Name: transfer_to_research_agent

Successfully transferred to research_agent


Update from node research_agent:


================================== Ai Message ==================================
Name: research_agent

- US GDP in 2024: $29.017 trillion (nominal, current prices)
- New York state GDP in 2024: $2.284 trillion
- New York state's share of US GDP in 2024: 7.87%


Update from node supervisor:


================================= Tool Message =================================
Name: transfer_to_math_agent

Successfully transferred to math_agent


Update from node math_agent:


================================== Ai Message ==================================
Name: math_agent

US GDP in 2024: $29.017 trillion
New York state GDP in 2024: $2.284 trillion
New York state's share of US GDP: 7.87%


Update from node supervisor:


================================== Ai Message ==================================
Name: supervisor

US GDP in 2024 was $29.017 trillion. New York state GDP in 2024 was $2.284 trillion. New York state's GDP was about 7.87% of the US GDP.
让我们查看完整的消息历史记录

for message in final_message_history:
    message.pretty_print()

================================ Human Message =================================

find US and New York state GDP in 2024. what % of US GDP was New York state?
================================== Ai Message ==================================
Name: supervisor
Tool Calls:
  transfer_to_research_agent (call_qxk9abrxWYQT6a9hPNpXiuM0)
 Call ID: call_qxk9abrxWYQT6a9hPNpXiuM0
  Args:
================================= Tool Message =================================
Name: transfer_to_research_agent

Successfully transferred to research_agent
================================== Ai Message ==================================
Name: research_agent
Tool Calls:
  tavily_search (call_A3cVm1BXDD8dYv6uLwO132gg)
 Call ID: call_A3cVm1BXDD8dYv6uLwO132gg
  Args:
    query: US GDP 2024
    search_depth: advanced
  tavily_search (call_77JyoUYwGDXlRNKOwvQFUUYJ)
 Call ID: call_77JyoUYwGDXlRNKOwvQFUUYJ
  Args:
    query: New York state GDP 2024
    search_depth: advanced
================================= Tool Message =================================
Name: tavily_search

{"query": "US GDP 2024", "follow_up_questions": null, "answer": null, "images": [], "results": [{"url": "https://tradingeconomics.com/united-states/gdp-growth", "title": "United States GDP Growth Rate - Trading Economics", "content": "The US economy expanded an annualized 2.4% in Q4 2024, slightly higher than 2.3% in the previous estimates, primarily reflecting a downward revision to imports. Exports fell slightly less (-0.2% vs -0.5%) and imports declined more than initially anticipated (-1.9% vs -1.2%), leaving the contribution from net trade positive at 0.26 pp (vs 0.12 pp). Government expenditure also rose more (3.1% vs 2.9%) and fixed investment contracted less (-1.1% vs -1.4%), due to equipment (-8.7% vs -9%) while [...] The Gross Domestic Product (GDP) in the United States expanded 2.40 percent in the fourth quarter of 2024 over the previous quarter. GDP Growth Rate in the United States averaged 3.21 percent from 1947 until 2024, reaching an all time high of 35.20 percent in the third quarter of 2020 and a record low of -28.10 percent in the second quarter of 2020. This page provides the latest reported value for - United States GDP Growth Rate - plus previous releases, historical high and low, short-term [...] The Gross Domestic Product (GDP) in the United States expanded 2.40 percent in the fourth quarter of 2024 over the previous quarter. GDP Growth Rate in the United States is expected to be 0.90 percent by the end of this quarter, according to Trading Economics global macro models and analysts expectations. In the long-term, the United States GDP Growth Rate is projected to trend around 2.00 percent in 2026, according to our econometric models.\n%\n3Y5Y10YMAX\nExport API\nOK\nLoading...", "score": 0.9071234, "raw_content": null}, {"url": "https://www.bea.gov/data/gdp/gross-domestic-product", "title": "Gross Domestic Product | U.S. Bureau of Economic Analysis (BEA)", "content": "Real gross domestic product (GDP) increased at an annual rate of 2.4 percent in the fourth quarter of 2024 (October, November, and December), according to the third estimate released by the U.S. Bureau of Economic Analysis. In the third quarter, real GDP increased 3.1 percent. The increase in real GDP in the fourth quarter primarily reflected increases in consumer spending and government spending that were partly offset by a decrease in investment. Imports, which are a subtraction in the", "score": 0.9008183, "raw_content": null}, {"url": "https://www.nerdwallet.com/article/finance/gdp-report", "title": "GDP Report: Final Estimate Shows Growth Increased 2.4% in Q4 2024", "content": "NerdWallet's content is fact-checked for accuracy, timeliness and relevance. It undergoes a thorough review process involving writers and editors to ensure the information is as clear and complete as possible.\n\nAnna Helhoski\n\nRick VanderKnyff\n\nUpdated on April 7\n\nReal gross domestic product increased by an annual rate of 2.4% in the fourth quarter of 2024, according to the third estimate report released on March 27 by the Bureau of Economic Analysis. [...] The third estimate also showed that in 2024, the U.S. GDP grew 2.8% compared to a 2.9% increase in 2023.\n\nQ1 2025 GDP forecasts are negative\n\nA forecasting tool published by the Atlanta Federal Reserve shows negative growth for the first quarter of 2025; it expects gross domestic product (GDP) to contract by rate of -2.8%, according to data released on March 28. If the forecast is correct, it would be the first quarter where GDP declined since the first and second quarters of 2022. [...] GDP could be the next concern: On March 3, a forecasting tool published by the Atlanta Federal Reserve showed that GDP could contract by a rate of -2.8% in the first quarter of 2025. If GDP does indeed decline, it would be the first time since the first and second quarters of 2022.\n\nIn 2024, the U.S. GDP grew 2.8% compared to a 2.9% increase in 2023, according to a second estimate of real gross domestic product from the Bureau of Economic Analysis, released Feb. 27.", "score": 0.89053273, "raw_content": null}], "response_time": 1.78}
================================= Tool Message =================================
Name: tavily_search

{"query": "New York state GDP 2024", "follow_up_questions": null, "answer": null, "images": [], "results": [{"url": "https://en.wikipedia.org/wiki/Economy_of_New_York_(state)", "title": "Economy of New York (state) - Wikipedia", "content": "Jump to content\nMain menu\nSearch\nDonate\nCreate account\nLog in\nPersonal tools\nToggle the table of contents\nEconomy of New York (state)\n1 language\nArticle\nTalk\nRead\nEdit\nView history\nTools\nFrom Wikipedia, the free encyclopedia\nThis article is about the overall economy of New York State. For the economy of New York City, see Economy of New York City.\nEconomy of New York\nNew York City, the economic capital of New York (state)\nStatistics\nGDP $2.3 trillion (2024)[1]\nGDP per capita  $117,332 (2024)[2] [...] The economy of the State of New York is reflected in its gross state product in 2024 of $2.284 trillion, ranking third in size behind the larger states of California and Texas. If New York State were an independent nation, it would rank as the 10th largest economy in the world by nominal GDP. However, in 2019, the multi-state, New York City-centered metropolitan statistical area produced a gross metropolitan product (GMP) of $US2.0 trillion, ranking first nationally by a wide margin and would [...] Population below poverty line   13.6%[3]\nGini coefficient    0.5157 ± 0.0029 (2023)[4]\nLabour force    9,645,984 (2023)[5]\nUnemployment    4.4% (August 2024)[6]\nPublic finances\nRevenues    $63.5 billion[7]\nExpenses    $54.6 billion[8]", "score": 0.9511106, "raw_content": null}, {"url": "https://en.wikipedia.org/wiki/List_of_U.S._states_and_territories_by_GDP", "title": "List of U.S. states and territories by GDP - Wikipedia", "content": "GDP per capita also varied widely throughout the United States in 2024, with New York ($117,332), Massachusetts ($110,561), and Washington (state) ($108,468) recording the three highest GDP per capita figures in the U.S., while Mississippi ($53,061), Arkansas ($60,276), and West Virginia ($60,783) recorded the three lowest GDP per capita figures in the U.S. The District of Columbia, though, recorded a GDP per capita figure far higher than any U.S. state in 2024 at $263,220. [...] Overall, in the calendar year 2024, the United States' Nominal GDP at Current Prices totaled at $29.017 trillion, as compared to $25.744 trillion in 2022.\nThe three U.S. states with the highest GDPs were California ($4.080 trillion), Texas ($2.695 trillion), and New York ($2.284 trillion). The three U.S. states with the lowest GDPs were Vermont ($45.4 billion), Wyoming ($53.0 billion), and Alaska ($69.8 billion).", "score": 0.8947989, "raw_content": null}, {"url": "https://edc.nyc/sites/default/files/2025-01/NYCEDC-State-of-the-NYC-Economy-2024-v3.pdf", "title": "[PDF] State of the New York City Economy - NYCEDC", "content": "for talent faced a limited supply. STATE OF THE NEW YORK CITY ECONOMY 2024 / 21 STATE OF THE NEW YORK CITY ECONOMY 2024 / 22 After losing nearly a million jobs during the COVID-19 pandemic, New York City is now at record-high levels of private and total employment. The city’s gross city product (GCP) stands at $1.18 trillion as of 2023.24 While legacy sectors such as Finance and Insurance have continued to play a vital part in the city’s economic successes, emerging sectors like Tech, the Green [...] STATE OF THE NEW YORK CITY ECONOMY 2024 / 11 New York City’s economy is the largest in the nation, with $2 trillion in gross metropolitan product (GMP) for the metro area, representing 9% of the total US economy. As such, the city’s economy is closely intertwined with the broader national economic landscape, and US macroeconomic conditions play a significant role in shaping the economic backdrop for the city. National interest rates, inflation, gross domestic product (GDP), and employment [...] 1 Macro Trends STATE OF THE NEW YORK CITY ECONOMY 2024 / 12 Output Has Grown Faster in NYC than Nationally Since 2022 Actual and Projected US Real GDP and NYC Real GCP Growth Rates 2019 2020 2021 2022 2023 2024* 2025* NYC 2.6% -4.2% 5.5% 2.6% 2.8% 3.6% 1.9% US 2.5% -2.2% 5.8% 1.9% 2.5% 2.5% 1.4% Source: NYC OMB and US Bureau of Economic Analysis. Projections for 2024 and and 2025 from NYC OMB.", "score": 0.85797083, "raw_content": null}], "response_time": 0.63}
================================== Ai Message ==================================
Name: research_agent

- US GDP in 2024: $29.017 trillion (nominal, current prices)
- New York state GDP in 2024: $2.284 trillion
- New York state's share of US GDP in 2024: 7.87%
================================== Ai Message ==================================
Name: supervisor
Tool Calls:
  transfer_to_math_agent (call_m5ICqaoAtRXHWb8BI3638dJL)
 Call ID: call_m5ICqaoAtRXHWb8BI3638dJL
  Args:
================================= Tool Message =================================
Name: transfer_to_math_agent

Successfully transferred to math_agent
================================== Ai Message ==================================
Name: math_agent
Tool Calls:
  divide (call_Sf7nvyvEgIaoDlaioPmkCdqz)
 Call ID: call_Sf7nvyvEgIaoDlaioPmkCdqz
  Args:
    a: 2.284
    b: 29.017
================================= Tool Message =================================
Name: divide

0.07871247889168417
================================== Ai Message ==================================
Name: math_agent

US GDP in 2024: $29.017 trillion
New York state GDP in 2024: $2.284 trillion
New York state's share of US GDP: 7.87%
================================== Ai Message ==================================
Name: supervisor

US GDP in 2024 was $29.017 trillion. New York state GDP in 2024 was $2.284 trillion. New York state's GDP was about 7.87% of the US GDP.

重要

您可以看到主管系统将所有单个智能体的消息（即，它们的内部工具调用循环）附加到完整的消息历史记录中。这意味着在每个主管回合，主管智能体都会看到这个完整的历史记录。如果您想更精细地控制

  • 如何将输入传递给智能体：您可以使用 LangGraph Send() 原语在交接期间直接将数据发送给工作智能体。请参阅下面的任务委派示例

  • 如何添加智能体输出：您可以通过将智能体包装在一个单独的节点函数中，来控制将智能体的内部消息历史记录的多少添加到整体主管消息历史记录中

    def call_research_agent(state):
    # return agent's final response,
    # excluding inner monologue
    response = research_agent.invoke(state)
    return {"messages": response["messages"][-1]}

4. 创建委派任务

到目前为止，单个智能体依赖于解释完整的消息历史记录来确定它们的任务。另一种方法是要求主管明确地制定任务。我们可以通过向 handoff_tool 函数添加一个 task_description 参数来实现这一点。

API 参考: Send

from langgraph.types import Send


def create_task_description_handoff_tool(
    *, agent_name: str, description: str | None = None
):
    name = f"transfer_to_{agent_name}"
    description = description or f"Ask {agent_name} for help."

    @tool(name, description=description)
    def handoff_tool(
        # this is populated by the supervisor LLM
        task_description: Annotated[
            str,
            "Description of what the next agent should do, including all of the relevant context.",
        ],
        # these parameters are ignored by the LLM
        state: Annotated[MessagesState, InjectedState],
    ) -> Command:
        task_description_message = {"role": "user", "content": task_description}
        agent_input = {**state, "messages": [task_description_message]}
        return Command(
            goto=[Send(agent_name, agent_input)],
            graph=Command.PARENT,
        )

    return handoff_tool


assign_to_research_agent_with_description = create_task_description_handoff_tool(
    agent_name="research_agent",
    description="Assign task to a researcher agent.",
)

assign_to_math_agent_with_description = create_task_description_handoff_tool(
    agent_name="math_agent",
    description="Assign task to a math agent.",
)

supervisor_agent_with_description = create_react_agent(
    model="openai:gpt-4.1",
    tools=[
        assign_to_research_agent_with_description,
        assign_to_math_agent_with_description,
    ],
    prompt=(
        "You are a supervisor managing two agents:\n"
        "- a research agent. Assign research-related tasks to this assistant\n"
        "- a math agent. Assign math-related tasks to this assistant\n"
        "Assign work to one agent at a time, do not call agents in parallel.\n"
        "Do not do any work yourself."
    ),
    name="supervisor",
)

supervisor_with_description = (
    StateGraph(MessagesState)
    .add_node(
        supervisor_agent_with_description, destinations=("research_agent", "math_agent")
    )
    .add_node(research_agent)
    .add_node(math_agent)
    .add_edge(START, "supervisor")
    .add_edge("research_agent", "supervisor")
    .add_edge("math_agent", "supervisor")
    .compile()
)

注意

我们在 handoff_tool 中使用了 Send() 原语。这意味着每个工作智能体不会接收完整的 supervisor 图状态作为输入，而只会看到 Send payload 的内容。在这个例子中，我们将任务描述作为一条单独的“human”消息发送。

现在让我们使用相同的输入查询来运行它

for chunk in supervisor.stream(
    {
        "messages": [
            {
                "role": "user",
                "content": "find US and New York state GDP in 2024. what % of US GDP was New York state?",
            }
        ]
    },
    subgraphs=True,
):
    pretty_print_messages(chunk, last_message=True)

Update from subgraph supervisor:


    Update from node agent:


    ================================== Ai Message ==================================
    Name: supervisor
    Tool Calls:
      transfer_to_research_agent (call_TtKzjGQBe4X9Xh0VzmjStVgZ)
     Call ID: call_TtKzjGQBe4X9Xh0VzmjStVgZ
      Args:


Update from subgraph research_agent:


    Update from node agent:


    ================================== Ai Message ==================================
    Name: research_agent
    Tool Calls:
      tavily_search (call_AfeRYBJxJtmD4EKqifYcx8EI)
     Call ID: call_AfeRYBJxJtmD4EKqifYcx8EI
      Args:
        query: US GDP in 2024
        search_depth: advanced
      tavily_search (call_n7Dn8QnDLu2ZpEDzswS2MOJ8)
     Call ID: call_n7Dn8QnDLu2ZpEDzswS2MOJ8
      Args:
        query: New York state GDP in 2024
        search_depth: advanced


Update from subgraph research_agent:


    Update from node tools:


    ================================= Tool Message =================================
    Name: tavily_search

    {"query": "New York state GDP in 2024", "follow_up_questions": null, "answer": null, "images": [], "results": [{"url": "https://en.wikipedia.org/wiki/Economy_of_New_York_(state)", "title": "Economy of New York (state) - Wikipedia", "content": "Jump to content\nMain menu\nSearch\nDonate\nCreate account\nLog in\nPersonal tools\nToggle the table of contents\nEconomy of New York (state)\n1 language\nArticle\nTalk\nRead\nEdit\nView history\nTools\nFrom Wikipedia, the free encyclopedia\nThis article is about the overall economy of New York State. For the economy of New York City, see Economy of New York City.\nEconomy of New York\nNew York City, the economic capital of New York (state)\nStatistics\nGDP $2.3 trillion (2024)[1]\nGDP per capita  $117,332 (2024)[2] [...] The economy of the State of New York is reflected in its gross state product in 2024 of $2.284 trillion, ranking third in size behind the larger states of California and Texas. If New York State were an independent nation, it would rank as the 10th largest economy in the world by nominal GDP. However, in 2019, the multi-state, New York City-centered metropolitan statistical area produced a gross metropolitan product (GMP) of $US2.0 trillion, ranking first nationally by a wide margin and would [...] Population below poverty line   13.6%[3]\nGini coefficient    0.5157 ± 0.0029 (2023)[4]\nLabour force    9,645,984 (2023)[5]\nUnemployment    4.4% (August 2024)[6]\nPublic finances\nRevenues    $63.5 billion[7]\nExpenses    $54.6 billion[8]", "score": 0.9530353, "raw_content": null}, {"url": "https://en.wikipedia.org/wiki/List_of_U.S._states_and_territories_by_GDP", "title": "List of U.S. states and territories by GDP - Wikipedia", "content": "GDP per capita also varied widely throughout the United States in 2024, with New York ($117,332), Massachusetts ($110,561), and Washington (state) ($108,468) recording the three highest GDP per capita figures in the U.S., while Mississippi ($53,061), Arkansas ($60,276), and West Virginia ($60,783) recorded the three lowest GDP per capita figures in the U.S. The District of Columbia, though, recorded a GDP per capita figure far higher than any U.S. state in 2024 at $263,220. [...] Overall, in the calendar year 2024, the United States' Nominal GDP at Current Prices totaled at $29.017 trillion, as compared to $25.744 trillion in 2022.\nThe three U.S. states with the highest GDPs were California ($4.080 trillion), Texas ($2.695 trillion), and New York ($2.284 trillion). The three U.S. states with the lowest GDPs were Vermont ($45.4 billion), Wyoming ($53.0 billion), and Alaska ($69.8 billion).", "score": 0.89997756, "raw_content": null}, {"url": "https://edc.nyc/sites/default/files/2025-01/NYCEDC-State-of-the-NYC-Economy-2024-v3.pdf", "title": "[PDF] State of the New York City Economy - NYCEDC", "content": "for talent faced a limited supply. STATE OF THE NEW YORK CITY ECONOMY 2024 / 21 STATE OF THE NEW YORK CITY ECONOMY 2024 / 22 After losing nearly a million jobs during the COVID-19 pandemic, New York City is now at record-high levels of private and total employment. The city’s gross city product (GCP) stands at $1.18 trillion as of 2023.24 While legacy sectors such as Finance and Insurance have continued to play a vital part in the city’s economic successes, emerging sectors like Tech, the Green [...] STATE OF THE NEW YORK CITY ECONOMY 2024 / 11 New York City’s economy is the largest in the nation, with $2 trillion in gross metropolitan product (GMP) for the metro area, representing 9% of the total US economy. As such, the city’s economy is closely intertwined with the broader national economic landscape, and US macroeconomic conditions play a significant role in shaping the economic backdrop for the city. National interest rates, inflation, gross domestic product (GDP), and employment [...] 1 Macro Trends STATE OF THE NEW YORK CITY ECONOMY 2024 / 12 Output Has Grown Faster in NYC than Nationally Since 2022 Actual and Projected US Real GDP and NYC Real GCP Growth Rates 2019 2020 2021 2022 2023 2024* 2025* NYC 2.6% -4.2% 5.5% 2.6% 2.8% 3.6% 1.9% US 2.5% -2.2% 5.8% 1.9% 2.5% 2.5% 1.4% Source: NYC OMB and US Bureau of Economic Analysis. Projections for 2024 and and 2025 from NYC OMB.", "score": 0.8616433, "raw_content": null}], "response_time": 2.35}


Update from subgraph research_agent:


    Update from node agent:


    ================================== Ai Message ==================================
    Name: research_agent

    - US GDP in 2024 was $29.017 trillion (nominal, current prices) ([source](https://en.wikipedia.org/wiki/List_of_U.S._states_and_territories_by_GDP)).
    - New York State GDP in 2024 was $2.284 trillion ([source](https://en.wikipedia.org/wiki/Economy_of_New_York_(state))).

    Percentage of US GDP attributed to New York State in 2024: approximately 7.9%.


Update from subgraph supervisor:


    Update from node agent:


    ================================== Ai Message ==================================
    Name: supervisor
    Tool Calls:
      transfer_to_math_agent (call_oYbIXhQQeTWlj2zvZSoStUgO)
     Call ID: call_oYbIXhQQeTWlj2zvZSoStUgO
      Args:


Update from subgraph math_agent:


    Update from node agent:


    ================================== Ai Message ==================================
    Name: math_agent
    Tool Calls:
      divide (call_K5QxmkQYFfCZw5Vzkbz43VIG)
     Call ID: call_K5QxmkQYFfCZw5Vzkbz43VIG
      Args:
        a: 2.284
        b: 29.017


Update from subgraph math_agent:


    Update from node tools:


    ================================= Tool Message =================================
    Name: divide

    0.07871247889168417


Update from subgraph math_agent:


    Update from node agent:


    ================================== Ai Message ==================================
    Name: math_agent

    New York state's GDP was approximately 7.87% of US GDP in 2024.


Update from subgraph supervisor:


    Update from node agent:


    ================================== Ai Message ==================================
    Name: supervisor

    Here are the findings:
    - US GDP in 2024: $29.017 trillion
    - New York State GDP in 2024: $2.284 trillion
    - New York State accounted for approximately 7.87% of US GDP in 2024.

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