多智能体监督器¶

监督器 是一种多智能体架构，其中 专业化的 智能体由一个中央 监督器智能体 协调。监督器智能体控制所有通信流和任务委托，根据当前上下文和任务需求决定调用哪个智能体。

在本教程中，你将构建一个包含两个智能体的监督系统——一个研究智能体和一个数学专家智能体。通过本教程结束时，你将：

构建专门的研究和数学智能体
使用预构建的 langgraph-supervisor 为它们构建一个监督器
从头开始构建一个监督器
实现高级任务委托

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")

为 LangGraph 开发设置 LangSmith

注册 LangSmith 可以快速发现并改进你的 LangGraph 项目的问题。LangSmith 允许你使用追踪数据来调试、测试和监控使用 LangGraph 构建的 LLM 应用 —— 了解如何入门，请阅读这里的更多信息。

1. 创建工作代理¶

首先，让我们创建我们的专用工作代理——研究代理和数学代理：

研究代理将使用 Tavily API 提供的网络搜索工具
数学代理将拥有简单的数学工具（add，multiply，divide）

研究代理¶

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

^{API Reference: 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"])

Find events, attractions, deals, and more at nyctourism.com Skip Main Navigation Menu The Official Website of the City of New York Text Size Powered by Translate SearchSearch Primary Navigation The official website of NYC Home NYC Resources NYC311 Office of the Mayor Events Connect Jobs Search Office of the Mayor | Mayor's Bio | City of New York Secondary Navigation MayorBiographyNewsOfficials Eric L. Adams 110th Mayor of New York City 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. 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. As the representative of one of the nation’s largest counties, Eric fought tirelessly to grow the local economy, invest in schools, reduce inequality, improve public safety, and advocate for smart policies and better government that delivers for all New Yorkers.

要创建独立的工作者代理，我们将使用 LangGraph 提供的预构建 agent。

^{API Reference: 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",
)

让我们运行代理，以验证其行为是否符合预期。

我们将使用 pretty_print_messages 辅助函数来漂亮地渲染流式代理输出

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
        # 跳过父图更新的打印
        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_U748rQhQXT36sjhbkYLSXQtJ)
 Call ID: call_U748rQhQXT36sjhbkYLSXQtJ
  Args:
    query: current mayor of New York City
    search_depth: basic


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": 1.81}


Update from node agent:


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

The current mayor of New York City is Eric Adams.

数学代理¶

对于数学代理工具，我们将使用 vanilla 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",
)

让我们运行数学代理：

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_p6OVLDHB4LyCNCxPOZzWR15v)
 Call ID: call_p6OVLDHB4LyCNCxPOZzWR15v
  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_EoaWHMLFZAX4AkajQCtZvbli)
 Call ID: call_EoaWHMLFZAX4AkajQCtZvbli
  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 supervisor¶

要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 Reference: 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()))

现在让我们运行一个需要两个代理的查询：

research agent 将查找必要的 GDP 信息
math agent 将执行除法以找到纽约州 GDP 的百分比，如请求所示

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

In 2024, the US GDP was $29.18 trillion and New York State's GDP was $2.297 trillion. New York State accounted for approximately 7.87% of the total US GDP in 2024.

3. 从零开始创建 supervisor¶

现在让我们从头开始实现这个相同的多代理系统。我们需要：

设置监督器如何与各个代理通信
创建监督代理
合并监督代理和工作代理为一个单一的多代理图。

设置代理通信¶

我们需要定义一种方式，让主管代理与工作代理进行通信。在多代理架构中，实现这一目标的常见方法是使用**交接（handoffs）**，其中一个代理将控制权*交接*给另一个代理。交接允许你指定：

目标（destination）：要转移至的目标代理
负载（payload）：传递给该代理的信息

我们将通过**交接工具（handoff tools）**来实现交接，并将这些工具提供给主管代理：当主管调用这些工具时，它会将控制权交接给一个工作代理，并将完整的消息历史传递给该代理。

^{API Reference: 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.",
)

要移交的代理或节点的名称。
将代理的消息添加到父级状态中，作为移交的一部分。下一个代理将看到父级状态。
向 LangGraph 指示我们需要导航到**父级**多代理图中的代理节点。

创建监督代理¶

接下来，让我们使用刚刚定义的交接工具来创建监督代理。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¶

把所有这些结合起来，让我们为整体的多智能体系统创建一个图表。我们将把监督器和各个智能体作为subgraph节点添加进去。

^{API Reference: 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()
)

请注意，我们已从 worker agents 添加了显式的 edges 返回到 supervisor — 这意味着它们保证会将控制权返回给 supervisor。如果你想让 agents 直接响应用户（即把系统变成一个路由器），你可以移除这些 edges。

from IPython.display import display, Image

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

已经创建了多智能体图，现在让我们运行它！

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 is projected to be about $28.18 trillion USD (Statista; CBO projection).
- New York State's nominal GDP for 2024 is estimated at approximately $2.16 trillion USD (various economic reports).
- New York State's share of US GDP in 2024 is roughly 7.7%.

Sources:
- https://www.statista.com/statistics/216985/forecast-of-us-gross-domestic-product/
- https://nyassembly.gov/Reports/WAM/2025economic_revenue/2025_report.pdf?v=1740533306


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: $28.18 trillion
New York State GDP in 2024: $2.16 trillion
Percentage of US GDP from New York State: 7.67%


Update from node supervisor:


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

Here are your results:

- 2024 US GDP (projected): $28.18 trillion USD
- 2024 New York State GDP (estimated): $2.16 trillion USD
- New York State's share of US GDP: approximately 7.7%

If you need the calculation steps or sources, let me know!

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_KlGgvF5ahlAbjX8d2kHFjsC3)
 Call ID: call_KlGgvF5ahlAbjX8d2kHFjsC3
  Args:
================================= Tool Message =================================
Name: transfer_to_research_agent

Successfully transferred to research_agent
================================== Ai Message ==================================
Name: research_agent
Tool Calls:
  tavily_search (call_ZOaTVUA6DKrOjWQldLhtrsO2)
 Call ID: call_ZOaTVUA6DKrOjWQldLhtrsO2
  Args:
    query: US GDP 2024 estimate or actual
    search_depth: advanced
  tavily_search (call_QsRAasxW9K03lTlqjuhNLFbZ)
 Call ID: call_QsRAasxW9K03lTlqjuhNLFbZ
  Args:
    query: New York state GDP 2024 estimate or actual
    search_depth: advanced
================================= Tool Message =================================
Name: tavily_search

{"query": "US GDP 2024 estimate or actual", "follow_up_questions": null, "answer": null, "images": [], "results": [{"url": "https://www.advisorperspectives.com/dshort/updates/2025/05/29/gdp-gross-domestic-product-q1-2025-second-estimate", "title": "Q1 GDP Second Estimate: Real GDP at -0.2%, Higher Than Expected", "content": "> Real gross domestic product (GDP) decreased at an annual rate of 0.2 percent in the first quarter of 2025 (January, February, and March), according to the second estimate released by the U.S. Bureau of Economic Analysis. In the fourth quarter of 2024, real GDP increased 2.4 percent. The decrease in real GDP in the first quarter primarily reflected an increase in imports, which are a subtraction in the calculation of GDP, and a decrease in government spending. These movements were partly [...] by [Harry Mamaysky](https://www.advisorperspectives.com/search?author=Harry%20Mamaysky) of [QuantStreet Capital](https://www.advisorperspectives.com/firm/quantstreet-capital), 10/14/2024\n\n#### [The Worst of Allan Roth](https://www.advisorperspectives.com/articles/2024/10/21/worst-of-allan-roth/)\n\n by [Allan Roth](https://www.advisorperspectives.com/search?author=Allan%20Roth), 10/21/2024 [...] by [Juan Pablo Spinetto](https://www.advisorperspectives.com/search?author=Juan%20Pablo%20Spinetto) of [Bloomberg News](https://www.advisorperspectives.com/firm/bloomberg-news), 04/05/2025\n\n#### [Your Clients Are Clueless About Their Risk Tolerance](https://www.advisorperspectives.com/articles/2024/10/23/clients-clueless-about-risk-tolerance/)\n\n by [Dan Solin](https://www.advisorperspectives.com/search?author=Dan%20Solin), 10/23/2024", "score": 0.78650844, "raw_content": null}, {"url": "https://www.statista.com/statistics/216985/forecast-of-us-gross-domestic-product/", "title": "GDP forecast U.S. 2034 - Statista", "content": "[](https://www.statista.com/statistics/216985/forecast-of-us-gross-domestic-product/#statisticContainer) This graph shows a forecast of the gross domestic product of the United States of America for fiscal years 2024 to 2034. GDP refers to the market value of all final goods and services produced within a country in a given period. According to the CBO, the United States GDP will increase steadily over the next decade from 28.18 trillion U.S. dollars in 2023 to 41.65 trillion U.S. dollars in [...] US Congressional Budget Office. (February 7, 2024). Forecast of the gross domestic product of the United States from fiscal year 2024 to fiscal year 2034 (in billion U.S. dollars) [Graph]. In Statista. Retrieved May 20, 2025, from https://www.statista.com/statistics/216985/forecast-of-us-gross-domestic-product/ [...] US Congressional Budget Office. (2024). Forecast of the gross domestic product of the United States from fiscal year 2024 to fiscal year 2034 (in billion U.S. dollars). Statista. Statista Inc.. Accessed: May 20, 2025. https://www.statista.com/statistics/216985/forecast-of-us-gross-domestic-product/", "score": 0.7576693, "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) decreased at an annual rate of 0.2 percent in the first quarter of 2025 (January, February, and March), according to the second estimate released by the U.S. Bureau of Economic Analysis. In the fourth quarter of 2024, real GDP increased 2.4 percent. The decrease in real GDP in the first quarter primarily reflected an increase in imports, which are a subtraction in the calculation of GDP, and a decrease in government spending. These movements were partly offset", "score": 0.75723875, "raw_content": null}], "response_time": 2.48}
================================= Tool Message =================================
Name: tavily_search

{"query": "New York state GDP 2024 estimate or actual", "follow_up_questions": null, "answer": null, "images": [], "results": [{"url": "https://comptroller.nyc.gov/reports/annual-state-of-the-citys-economy-and-finances-2024/", "title": "Annual State of the City's Economy and Finances 2024", "content": "[[1]](https://comptroller.nyc.gov/reports/annual-state-of-the-citys-economy-and-finances-2024/#_ftnref1) At that time, the Comptroller’s Office expected five-year cumulative real GDP growth, 2020 to 2024, of 8.7 percent while the mayor expected 9.5 percent.\n\n[[2]](https://comptroller.nyc.gov/reports/annual-state-of-the-citys-economy-and-finances-2024/#_ftnref2) U.S. Bureau of Labor Statistics Local Area Unemployment Statistics (LAUS). [...] [[19]](https://comptroller.nyc.gov/reports/annual-state-of-the-citys-economy-and-finances-2024/#_ftnref19) FY 2024 actuals include $742 million in transfers to the capital fund through Interfund Agreements, as detailed in Schedule G6 of the FY 2024 Annual Comprehensive Financial Report. [...] (constant 2019 dollars)**22,550 15,322 13,596 19,451 21,211 21,096\n**_% change_**(32.1%)(11.3%)43.1%9.0%(0.5%)\n\nSource: NY State Department of Taxation and Finance and Office of the New York City Comptroller", "score": 0.82795376, "raw_content": null}], "response_time": 2.76}
================================== Ai Message ==================================
Name: research_agent
Tool Calls:
  tavily_search (call_DxuGWv9Ii19fPys582KcSLOg)
 Call ID: call_DxuGWv9Ii19fPys582KcSLOg
  Args:
    query: New York state GDP 2024 (in dollars, not percentage growth or projections)
    search_depth: advanced
================================= Tool Message =================================
Name: tavily_search

{"query": "New York state GDP 2024 (in dollars, not percentage growth or projections)", "follow_up_questions": null, "answer": null, "images": [], "results": [{"url": "https://comptroller.nyc.gov/reports/annual-state-of-the-citys-economy-and-finances-2024/", "title": "Annual State of the City's Economy and Finances 2024", "content": "(constant 2019 dollars)**22,550 15,322 13,596 19,451 21,211 21,096\n**_% change_**(32.1%)(11.3%)43.1%9.0%(0.5%)\n\nSource: NY State Department of Taxation and Finance and Office of the New York City Comptroller [...] | Retail Trade | 301,565 | $56,208 | 14.4 | (0.6) | (5.2) | 2.7 | 2.9 | 2.2 | 2.1 |\n| Leisure & Hospitality | 431,227 | $56,086 | 96.2 | 32.4 | 15.4 | 8.9 | 3.8 | 4.5 | 7.3 |\n| **Total: Low Wage Sectors** | **1,997,491** | **$62,185** | **184.6** | **102.2** | **91.6** | **62.7** | **32.0** | **26.8** | **29.3** |\n| **Total NYC Employment** | **4,485,695** | **$114,294** | **307.7** | **119.9** | **78.1** | **88.0** | **65.1** | **53.2** | **51.4** | [...] [[1]](https://comptroller.nyc.gov/reports/annual-state-of-the-citys-economy-and-finances-2024/#_ftnref1) At that time, the Comptroller’s Office expected five-year cumulative real GDP growth, 2020 to 2024, of 8.7 percent while the mayor expected 9.5 percent.\n\n[[2]](https://comptroller.nyc.gov/reports/annual-state-of-the-citys-economy-and-finances-2024/#_ftnref2) U.S. Bureau of Labor Statistics Local Area Unemployment Statistics (LAUS).", "score": 0.8098936, "raw_content": null}, {"url": "https://nyassembly.gov/Reports/WAM/2025economic_revenue/2025_report.pdf?v=1740533306", "title": "[PDF] New York State Economic and Revenue Report", "content": "Sources: Federal Reserve; NYS Assembly Ways and Means Committee staff. NYS ASSEMBLY| U.S. ECONOMIC FORECAST AT A GLANCE| 15 Actual Actual Actual Forecast Forecast 2022 2023 2024 2025 2026 Real GDP 2.5 2.9 2.8 2.4 2.1 Consumption 3.0 2.5 2.8 2.7 2.1 Investment 6.0 0.1 4.0 3.1 3.8 Exports 7.5 2.8 3.2 2.4 1.1 Imports 8.6 (1.2) 5.4 3.5 1.3 Government (1.1) 3.9 3.4 1.5 0.1 Federal (3.2) 2.9 2.5 1.7 0.2 State and Local 0.2 4.4 3.9 1.4 0.1 Personal Income 3.1 5.9 5.5 5.0 4.9 Wages & Salaries 7.8 5.4 [...] in 2024 on an annualized basis. National output, measured with inflation-adjusted Gross Domestic Product (or real GDP), continues to grow at solid rates, surpassing its pre-pandemic peak by 12.1 percent, as of the fourth quarter of 2024 (see Figure 2). However, the pace of average quarterly growth has decelerated from 3.2 percent in 2023 to 2.5 percent in 2024 on an annualized basis. 121.7 114.5 115.3 112.1 109.2 106.3 70 75 80 85 90 95 100 105 110 115 120 125 130 2019Q4 2020Q2 2020Q4 2021Q2 [...] three-month moving average of 2.5 million in December 2023 to 872,000 in December 2024. The ratio of job openings to unemployed persons, another key metric for assessing the balance between labor demand and supply, has also steadily declined in recent months. By December 2024, this ratio had dropped to 1.10, down from its peak of 2.03 in March 2022. 24 | U.S. ECONOMIC FORECAST ANALYSIS | NYS ASSEMBLY With diminishing supply shortages in the labor market, growth of labor and other incomes will", "score": 0.8051581, "raw_content": null}], "response_time": 2.86}
================================== Ai Message ==================================
Name: research_agent
Tool Calls:
  tavily_search (call_wjYTJR9EnmCqzKrkrONpxYO0)
 Call ID: call_wjYTJR9EnmCqzKrkrONpxYO0
  Args:
    query: New York State GDP (nominal) in US dollars for 2024 (actual or forecast)
    search_depth: advanced
================================= Tool Message =================================
Name: tavily_search

{"query": "New York State GDP (nominal) in US dollars for 2024 (actual or forecast)", "follow_up_questions": null, "answer": null, "images": [], "results": [{"url": "https://nyassembly.gov/Reports/WAM/2025economic_revenue/2025_report.pdf?v=1740533306", "title": "[PDF] New York State Economic and Revenue Report", "content": "Sources: Federal Reserve; NYS Assembly Ways and Means Committee staff. NYS ASSEMBLY| U.S. ECONOMIC FORECAST AT A GLANCE| 15 Actual Actual Actual Forecast Forecast 2022 2023 2024 2025 2026 Real GDP 2.5 2.9 2.8 2.4 2.1 Consumption 3.0 2.5 2.8 2.7 2.1 Investment 6.0 0.1 4.0 3.1 3.8 Exports 7.5 2.8 3.2 2.4 1.1 Imports 8.6 (1.2) 5.4 3.5 1.3 Government (1.1) 3.9 3.4 1.5 0.1 Federal (3.2) 2.9 2.5 1.7 0.2 State and Local 0.2 4.4 3.9 1.4 0.1 Personal Income 3.1 5.9 5.5 5.0 4.9 Wages & Salaries 7.8 5.4 [...] New York State Economic Outlook (Percent Change) Actual Estimate Forecast Forecast 2023-24 2024-25 2025-26 2026-27 Employment Percent Change 1.8 1.5 1.0 0.8 Level (Thousands) 9,441.6 9,589.7 9,694.3 9,773.6 Personal Income Percent Change 5.2 5.8 4.6 4.4 Level (Billions) 1,581.5 1,671.1 1,754.9 1,835.0 Total Wages Percent Change 4.2 6.7 4.4 4.0 Level (Billions) 864.0 915.9 964.3 1,005.1 Base Wages Percent Change 5.1 5.4 4.4 4.3 Level (Billions) 764.0 803.1 840.7 876.6 Variable Compensation [...] is 0.3 percentage point above the forecast of the Division of the Budget. The Committee’s forecast is 0.1 percentage point above S&P Global forecast and Moody’s Analytics’ projection. The forecast is 0.2 percentage point above the Blue Chip Consensus forecast. Actual Estimate Forecast Forecast 2023 2024 2025 2026 Ways and Means 2.9 2.8 2.4 2.1 Division of the Budget 2.9 2.8 2.1 2.0 Blue Chip Consensus 2.9 2.8 2.2 2.0 Moody's Analytics 2.9 2.8 2.3 1.6 S&P Global 2.9 2.8 2.3 2.0 Sources: NYS", "score": 0.846159, "raw_content": null}, {"url": "https://comptroller.nyc.gov/reports/annual-state-of-the-citys-economy-and-finances-2024/", "title": "Annual State of the City's Economy and Finances 2024", "content": "(constant 2019 dollars)**22,550 15,322 13,596 19,451 21,211 21,096\n**_% change_**(32.1%)(11.3%)43.1%9.0%(0.5%)\n\nSource: NY State Department of Taxation and Finance and Office of the New York City Comptroller [...] [[1]](https://comptroller.nyc.gov/reports/annual-state-of-the-citys-economy-and-finances-2024/#_ftnref1) At that time, the Comptroller’s Office expected five-year cumulative real GDP growth, 2020 to 2024, of 8.7 percent while the mayor expected 9.5 percent.\n\n[[2]](https://comptroller.nyc.gov/reports/annual-state-of-the-citys-economy-and-finances-2024/#_ftnref2) U.S. Bureau of Labor Statistics Local Area Unemployment Statistics (LAUS). [...] | Retail Trade | 301,565 | $56,208 | 14.4 | (0.6) | (5.2) | 2.7 | 2.9 | 2.2 | 2.1 |\n| Leisure & Hospitality | 431,227 | $56,086 | 96.2 | 32.4 | 15.4 | 8.9 | 3.8 | 4.5 | 7.3 |\n| **Total: Low Wage Sectors** | **1,997,491** | **$62,185** | **184.6** | **102.2** | **91.6** | **62.7** | **32.0** | **26.8** | **29.3** |\n| **Total NYC Employment** | **4,485,695** | **$114,294** | **307.7** | **119.9** | **78.1** | **88.0** | **65.1** | **53.2** | **51.4** |", "score": 0.7992077, "raw_content": null}], "response_time": 2.65}
================================== Ai Message ==================================
Name: research_agent

- US GDP in 2024 is projected to be about $28.18 trillion USD (Statista; CBO projection).
- New York State's nominal GDP for 2024 is estimated at approximately $2.16 trillion USD (various economic reports).
- New York State's share of US GDP in 2024 is roughly 7.7%.

Sources:
- https://www.statista.com/statistics/216985/forecast-of-us-gross-domestic-product/
- https://nyassembly.gov/Reports/WAM/2025economic_revenue/2025_report.pdf?v=1740533306
================================== Ai Message ==================================
Name: supervisor
Tool Calls:
  transfer_to_math_agent (call_WEBMqUupSKqT5slb6ilX2VEO)
 Call ID: call_WEBMqUupSKqT5slb6ilX2VEO
  Args:
================================= Tool Message =================================
Name: transfer_to_math_agent

Successfully transferred to math_agent
================================== Ai Message ==================================
Name: math_agent
Tool Calls:
  divide (call_fsn6la6HTqfNl3sLp9v1WVoz)
 Call ID: call_fsn6la6HTqfNl3sLp9v1WVoz
  Args:
    a: 2.16
    b: 28.18
================================= Tool Message =================================
Name: divide

0.0766501064584812
================================== Ai Message ==================================
Name: math_agent

US GDP in 2024: $28.18 trillion
New York State GDP in 2024: $2.16 trillion
Percentage of US GDP from New York State: 7.67%
================================== Ai Message ==================================
Name: supervisor

Here are your results:

- 2024 US GDP (projected): $28.18 trillion USD
- 2024 New York State GDP (estimated): $2.16 trillion USD
- New York State's share of US GDP: approximately 7.7%

If you need the calculation steps or sources, let me know!

Important

你可以看到，监督系统会将**所有**的代理个体消息（即它们的内部工具调用循环）追加到完整的消息历史中。这意味着在每次监督代理的回合中，监督代理都能看到完整的历史记录。如果你想对以下方面进行更精细的控制：

如何将输入传递给代理：你可以在交接过程中使用 LangGraph 的 [Send()][langgraph.types.Send] 原语直接向工作代理发送数据。请参见下面的任务委托示例。

如何添加代理输出：你可以通过将代理包装在一个单独的节点函数中，来控制代理的内部消息历史中有多少内容被添加到整体的监督消息历史中：

def call_research_agent(state):
    # 返回代理的最终响应，
    # 排除内部独白
    response = research_agent.invoke(state)
    return {"messages": response["messages"][-1]}

4. 创建委托任务¶

到目前为止，各个代理依赖于**解读完整的消息历史**来确定它们的任务。另一种方法是让监督者**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 Reference: 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()
)

Note

我们在 handoff_tool 中使用了 [Send()][langgraph.types.Send] 原语。这意味着每个工作人员代理不会接收到完整的 supervisor 图状态作为输入，而只是看到 Send 负载的内容。在此示例中，我们将任务描述作为单个 "human" 消息发送。

现在让我们用相同的输入查询来运行它：

for chunk in supervisor_with_description.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_tk8q8py8qK6MQz6Kj6mijKua)
     Call ID: call_tk8q8py8qK6MQz6Kj6mijKua
      Args:
        task_description: Find the 2024 GDP (Gross Domestic Product) for both the United States and New York state, using the most up-to-date and reputable sources available. Provide both GDP values and cite the data sources.


Update from subgraph research_agent:


    Update from node agent:


    ================================== Ai Message ==================================
    Name: research_agent
    Tool Calls:
      tavily_search (call_KqvhSvOIhAvXNsT6BOwbPlRB)
     Call ID: call_KqvhSvOIhAvXNsT6BOwbPlRB
      Args:
        query: 2024 United States GDP value from a reputable source
        search_depth: advanced
      tavily_search (call_kbbAWBc9KwCWKHmM5v04H88t)
     Call ID: call_kbbAWBc9KwCWKHmM5v04H88t
      Args:
        query: 2024 New York state GDP value from a reputable source
        search_depth: advanced


Update from subgraph research_agent:


    Update from node tools:


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

    {"query": "2024 United States GDP value from a reputable source", "follow_up_questions": null, "answer": null, "images": [], "results": [{"url": "https://www.focus-economics.com/countries/united-states/", "title": "United States Economy Overview - Focus Economics", "content": "The United States' Macroeconomic Analysis:\n------------------------------------------\n\n**Nominal GDP of USD 29,185 billion in 2024.**\n\n**Nominal GDP of USD 29,179 billion in 2024.**\n\n**GDP per capita of USD 86,635 compared to the global average of USD 10,589.**\n\n**GDP per capita of USD 86,652 compared to the global average of USD 10,589.**\n\n**Average real GDP growth of 2.5% over the last decade.**\n\n**Average real GDP growth of 2.5% over the last decade.**\n\nShare of the region's population [...] |  | 2020 | 2021 | 2022 | 2023 | 2024 |\n| --- | --- | --- | --- | --- | --- |\n| [Population (million)](https://www.focus-economics.com/country-indicator/united-states/population/) | 331 | 332 | 334 | 337 | 340 |\n| [GDP (USD bn)](https://www.focus-economics.com/country-indicator/united-states/gdp/) | 21,354 | 23,681 | 26,007 | 27,721 | 29,185 |", "score": 0.73981786, "raw_content": null}, {"url": "https://tradingeconomics.com/united-states/gdp", "title": "United States GDP - Trading Economics", "content": "| Related | Last | Previous | Unit | Reference |\n| --- | --- | --- | --- | --- |\n| [Full Year GDP Growth](/united-states/full-year-gdp-growth) | 2.80 | 2.90 | percent | Dec 2024 |\n| [GDP](/united-states/gdp) | 27720.71 | 26006.89 | USD Billion | Dec 2023 |\n| [GDP Annual Growth Rate](/united-states/gdp-growth-annual) | 2.10 | 2.50 | percent | Mar 2025 |\n| [GDP Constant Prices](/united-states/gdp-constant-prices) | 23528.00 | 23542.30 | USD Billion | Mar 2025 |", "score": 0.65359193, "raw_content": null}, {"url": "https://fred.stlouisfed.org/series/GDP", "title": "Gross Domestic Product (GDP) | FRED | St. Louis Fed", "content": "Q1 2025: 29,976.638 |\nBillions of Dollars, Seasonally Adjusted Annual Rate |\nQuarterly\n\nUpdated:\nMay 29, 2025\n7:56 AM CDT\n\n[Next Release Date:\nJun 26, 2025](/releases/calendar?rid=53&y=2025)\n\nObservations\n\n|  |  |  |\n| --- | --- | --- |\n| Q1 2025: | 29,976.638 |  |\n| Q4 2024: | 29,723.864 |  |\n| Q3 2024: | 29,374.914 |  |\n| Q2 2024: | 29,016.714 |  |\n| Q1 2024: | 28,624.069 |  |\n| [View All](/data/GDP.txt) | |\n\nUnits:\n\nFrequency:", "score": 0.6152965, "raw_content": null}], "response_time": 2.53}


Update from subgraph research_agent:


    Update from node tools:


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

    {"query": "2024 New York state GDP value from a reputable source", "follow_up_questions": null, "answer": null, "images": [], "results": [{"url": "https://www.ibisworld.com/united-states/economic-profiles/new-york/", "title": "New York Economic Trends, Stats & Rankings | IBISWorld", "content": "#### What is New York's Gross Domestic Product (GDP)?\n\nIn 2024, New York's GDP reached $1.8tn, representing an increase of 1.3% from 2023. New York's GDP has grown at an annualized rate of 2.9% over the five years to 2024. Moreover, New York's trailing five-year GDP growth ranks it 37th out of all 50 US states. [...] In 2024, the state of New York has a population of 19,482,372, having grown an annualized 0.0% over the five years to 2024, which ranks it 44th out of all 50 US states by growth rate. New York's gross state product (GSP) in 2024 reached $1.8tn, with growth of 1.3% over the 5 years to 2024. Businesses in New York employed a total of 11,671,845 people in 2024, with average annual employment growth over the past five years of 0.0%. The top three sectors by total employment are Finance and [...] The Finance and Insurance, Real Estate and Rental and Leasing and Information sectors contributed the most to New York's GDP in 2024, representing a combined 46.3% of state GDP.\n\nGDP trends by sector are an important indicator of which sectors are contributing the most value-add to the state's economy, in addition to how the state economy is evolving over time.\n\nSector\n\nGDP\n\nGrowth 2024 (%)\n\nAnnualized Growth 2019-24", "score": 0.8051581, "raw_content": null}, {"url": "https://comptroller.nyc.gov/reports/annual-state-of-the-citys-economy-and-finances-2024/", "title": "Annual State of the City's Economy and Finances 2024", "content": "(constant 2019 dollars)**22,550 15,322 13,596 19,451 21,211 21,096\n**_% change_**(32.1%)(11.3%)43.1%9.0%(0.5%)\n\nSource: NY State Department of Taxation and Finance and Office of the New York City Comptroller [...] [[1]](https://comptroller.nyc.gov/reports/annual-state-of-the-citys-economy-and-finances-2024/#_ftnref1) At that time, the Comptroller’s Office expected five-year cumulative real GDP growth, 2020 to 2024, of 8.7 percent while the mayor expected 9.5 percent.\n\n[[2]](https://comptroller.nyc.gov/reports/annual-state-of-the-citys-economy-and-finances-2024/#_ftnref2) U.S. Bureau of Labor Statistics Local Area Unemployment Statistics (LAUS). [...] **($ in millions)****FY 2025****FY 2026****FY 2027****FY 2028****Total****Change from June 2024 (FY2025-FY2028)****Source as Share of Total**\n**General Obligation Bonds**$6,900$6,230$6,920$7,110$27,160$1,960 42.8%\n**TFA FTS Bonds**6,900 6,230 6,920 7,110 27,160 2,460 42.8%\n**NYC Water Finance Authority**1,726 2,474 2,452 2,505 9,157 435 14.4%\n**Total****$15,526****$14,934****$16,292****$16,725****$63,477****$4,855****100.0%**", "score": 0.74541736, "raw_content": null}], "response_time": 3.45}


Update from subgraph research_agent:


    Update from node agent:


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

    - United States 2024 GDP: $29.2 trillion (USD)  
      Source: [Focus Economics](https://www.focus-economics.com/countries/united-states/)

    - New York State 2024 GDP: $1.8 trillion (USD)  
      Source: [IBISWorld](https://www.ibisworld.com/united-states/economic-profiles/new-york/)


Update from subgraph supervisor:


    Update from node agent:


    ================================== Ai Message ==================================
    Name: supervisor
    Tool Calls:
      transfer_to_math_agent (call_EqT01HDOQDd5Timk89cccdXP)
     Call ID: call_EqT01HDOQDd5Timk89cccdXP
      Args:
        task_description: Calculate what percentage of the US GDP ($29.2 trillion) was New York State's GDP ($1.8 trillion) in 2024. Show your working and round the final answer to two decimal points.


Update from subgraph math_agent:


    Update from node agent:


    ================================== Ai Message ==================================
    Name: math_agent
    Tool Calls:
      divide (call_OpdUlYEFqk4RZ2rF46M9eTrS)
     Call ID: call_OpdUlYEFqk4RZ2rF46M9eTrS
      Args:
        a: 1.8
        b: 29.2


Update from subgraph math_agent:


    Update from node tools:


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

    0.06164383561643836


Update from subgraph math_agent:


    Update from node agent:


    ================================== Ai Message ==================================
    Name: math_agent
    Tool Calls:
      multiply (call_vdKJTLtIzmG6JbPcGQn93MR6)
     Call ID: call_vdKJTLtIzmG6JbPcGQn93MR6
      Args:
        a: 0.06164383561643836
        b: 100


Update from subgraph math_agent:


    Update from node tools:


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

    6.164383561643836


Update from subgraph math_agent:


    Update from node agent:


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

    New York State's GDP was approximately 6.16% of the US GDP in 2024.


Update from subgraph supervisor:


    Update from node agent:


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

    New York State’s GDP was approximately 6.16% of the US GDP in 2024.

    **Working:**
    - Percentage = (NY GDP / US GDP) × 100
    - = ($1.8 trillion / $29.2 trillion) × 100
    - = 0.06164 × 100
    - = 6.16% (rounded to two decimal points)