如何向聊天机器人添加工具
本节将介绍如何创建对话代理：能够使用工具与其他系统和 API 交互的聊天机器人。
注意
本操作指南之前使用 RunnableWithMessageHistory 构建了一个聊天机器人。您可以在 v0.2 文档中访问此版本的指南。
从 LangChain v0.3 版本发布开始，我们建议 LangChain 用户利用 LangGraph 持久化功能，将 `memory` 集成到新的 LangChain 应用程序中。
如果您的代码已经依赖于 `RunnableWithMessageHistory` 或 `BaseChatMessageHistory`，则**无需**进行任何更改。我们不打算在近期弃用此功能，因为它适用于简单的聊天应用程序，并且任何使用 `RunnableWithMessageHistory` 的代码都将继续按预期工作。
请参阅如何迁移到LangGraph记忆了解更多详细信息。
设置
在本指南中，我们将使用一个工具调用代理，它带有一个用于网页搜索的工具。默认情况下，它将由Tavily提供支持，但您可以将其替换为任何类似的工具。本节的其余部分将假定您正在使用 Tavily。
您需要到 Tavily 网站注册一个账户，并安装以下包
%pip install --upgrade --quiet langchain-openai tavily-python langgraph
import getpass
import os
if not os.environ.get("OPENAI_API_KEY"):
os.environ["OPENAI_API_KEY"] = getpass.getpass("OpenAI API Key:")
if not os.environ.get("TAVILY_API_KEY"):
os.environ["TAVILY_API_KEY"] = getpass.getpass("Tavily API Key:")
您还需要将 OpenAI 密钥设置为 `OPENAI_API_KEY`，并将 Tavily API 密钥设置为 `TAVILY_API_KEY`。
创建代理
我们的最终目标是创建一个能够以对话方式回应用户问题，并在需要时查找信息的代理。
首先，让我们初始化 Tavily 和一个能够进行工具调用的 OpenAI 聊天模型
from langchain_openai import ChatOpenAI
from langchain_tavily import TavilySearch
tools = [TavilySearch(max_results=10, topic="general")]
# Choose the LLM that will drive the agent
# Only certain models support this
model = ChatOpenAI(model="gpt-4o-mini")
API 参考：ChatOpenAI
为了使我们的代理更具对话性，我们还可以指定一个提示。这是一个示例
prompt = (
"You are a helpful assistant. "
"You may not need to use tools for every query - the user may just want to chat!"
)
太好了！现在让我们使用 LangGraph 的预构建 create_react_agent 来组装我们的代理，它允许您创建一个 工具调用代理
from langgraph.prebuilt import create_react_agent
# prompt allows you to preprocess the inputs to the model inside ReAct agent
# in this case, since we're passing a prompt string, we'll just always add a SystemMessage
# with this prompt string before any other messages sent to the model
agent = create_react_agent(model, tools, prompt=prompt)
API 参考：create_react_agent
运行代理
现在我们已经设置好了代理，让我们尝试与它互动！它既可以处理无需查找的简单查询
from langchain_core.messages import HumanMessage
agent.invoke({"messages": [HumanMessage(content="I'm Nemo!")]})
API 参考：HumanMessage
{'messages': [HumanMessage(content="I'm Nemo!", additional_kwargs={}, response_metadata={}, id='40b60204-1af1-40d4-b6a7-b845a2281dd6'),
AIMessage(content='Hi Nemo! How can I assist you today?', additional_kwargs={'refusal': None}, response_metadata={'token_usage': {'completion_tokens': 11, 'prompt_tokens': 795, 'total_tokens': 806, 'completion_tokens_details': {'accepted_prediction_tokens': 0, 'audio_tokens': 0, 'reasoning_tokens': 0, 'rejected_prediction_tokens': 0}, 'prompt_tokens_details': {'audio_tokens': 0, 'cached_tokens': 0}}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_34a54ae93c', 'id': 'chatcmpl-BjsUwqprT2mVdjqu1aaSm1jVVWYVz', 'service_tier': 'default', 'finish_reason': 'stop', 'logprobs': None}, id='run--08282ec6-6d3e-4495-b004-b3b08f3879c3-0', usage_metadata={'input_tokens': 795, 'output_tokens': 11, 'total_tokens': 806, 'input_token_details': {'audio': 0, 'cache_read': 0}, 'output_token_details': {'audio': 0, 'reasoning': 0}})]}
或者，它可以使用传入的搜索工具在需要时获取最新信息
agent.invoke(
{
"messages": [
HumanMessage(
content="What is the current conservation status of the Great Barrier Reef?"
)
],
}
)
{'messages': [HumanMessage(content='What is the current conservation status of the Great Barrier Reef?', additional_kwargs={}, response_metadata={}, id='5240955c-d842-408d-af3d-4ee74db29dbd'),
AIMessage(content='', additional_kwargs={'tool_calls': [{'id': 'call_W37BFkNuZlJu9US1Tl71xpiX', 'function': {'arguments': '{"query":"current conservation status of the Great Barrier Reef","time_range":"year","topic":"general"}', 'name': 'tavily_search'}, 'type': 'function'}], 'refusal': None}, response_metadata={'token_usage': {'completion_tokens': 32, 'prompt_tokens': 804, 'total_tokens': 836, 'completion_tokens_details': {'accepted_prediction_tokens': 0, 'audio_tokens': 0, 'reasoning_tokens': 0, 'rejected_prediction_tokens': 0}, 'prompt_tokens_details': {'audio_tokens': 0, 'cached_tokens': 0}}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_34a54ae93c', 'id': 'chatcmpl-BjsV6EJ7F1vDipoG4dpEiBRZvuTLo', 'service_tier': 'default', 'finish_reason': 'tool_calls', 'logprobs': None}, id='run--5f5b32d7-fb80-4913-a7ec-ca9c5acaa101-0', tool_calls=[{'name': 'tavily_search', 'args': {'query': 'current conservation status of the Great Barrier Reef', 'time_range': 'year', 'topic': 'general'}, 'id': 'call_W37BFkNuZlJu9US1Tl71xpiX', 'type': 'tool_call'}], usage_metadata={'input_tokens': 804, 'output_tokens': 32, 'total_tokens': 836, 'input_token_details': {'audio': 0, 'cache_read': 0}, 'output_token_details': {'audio': 0, 'reasoning': 0}}),
ToolMessage(content='{"query": "current conservation status of the Great Barrier Reef", "follow_up_questions": null, "answer": null, "images": [], "results": [{"title": "The Great Barrier Reef: Current Conservation Efforts and Future Outlook", "url": "https://discoverwildscience.com/the-great-barrier-reef-current-conservation-efforts-and-future-outlook-1-279446/", "content": "The Great Barrier Reef, a mesmerizing marvel of nature, stretches over 2,300 kilometers along the northeast coast of Australia. As the largest coral reef system in the world, it is home to an incredible diversity of marine life, including more than 1,500 species of fish and 411 types of hard coral.", "score": 0.6353361, "raw_content": null}, {"title": "Monitoring progress - Protecting the Great Barrier Reef", "url": "https://www.detsi.qld.gov.au/great-barrier-reef/monitoring-progress", "content": "Stay informed about the current state of the Great Barrier Reef through comprehensive monitoring reports and reef report cards. Delve into the scientific research and advancements contributing to reef conservation. Learn about ongoing efforts to track progress and ensure the reef\'s long-term health.", "score": 0.6347929, "raw_content": null}, {"title": "Great Barrier Reef Outlook Report shows that the reef is in serious ...", "url": "https://biodiversitycouncil.org.au/news/great-barrier-reef-outlook-report-shows-that-the-reef-is-in-serious-trouble", "content": "The Great Barrier Reef is in very serious trouble. Climate change is the biggest threat to the reef. Catchment restoration activities that reduce sediment flowing to the reef will aid the health of the reef but cannot match the scale of destruction occurring due to marine heatwaves caused by climate change.", "score": 0.5183761, "raw_content": null}, {"title": "Water pollution threatens Great Barrier Reef\'s survival: new report ...", "url": "https://www.marineconservation.org.au/water-pollution-threatens-great-barrier-reefs-survival-new-report-highlights-funding-need/", "content": "While this investment has supported critical work across the Great Barrier Reef catchments, more funding is needed. At current rates, the target to cut fine sediment by 25% on 2009 levels will not be met until 2047, while the target to reduce dissolved inorganic nitrogen by 60% is not expected to be achieved until 2114.", "score": 0.51383984, "raw_content": null}, {"title": "What is the state of the Great Barrier Reef? - Tangaroa Blue", "url": "https://tangaroablue.org/the-state-of-the-great-barrier-reef/", "content": "The Great Barrier Reef Outlook Report 2024, prepared every five years by the Great Barrier Reef Marine Park Authority, summarises the Reef\'s long-term outlook based on its use, management, and risks.This year\'s report uses data from the Australian Marine Debris Initiative Database to analyse the risks and impacts of marine debris on the Great Barrier Reef and help identify areas for", "score": 0.47489962, "raw_content": null}, {"title": "New report on Great Barrier Reef shows coral cover increases before ...", "url": "https://www.aims.gov.au/information-centre/news-and-stories/new-report-great-barrier-reef-shows-coral-cover-increases-onset-serious-bleaching-cyclones", "content": "Coral cover has increased in all three regions on the Great Barrier Reef and is at regional highs in two of the three regions. But the results come with a note of caution. ... trained scientists during manta tow surveys and is a metric which allows AIMS scientists to provide an overview of the Great Barrier Reef\'s status and keep policy", "score": 0.40330887, "raw_content": null}, {"title": "Cycle of coral bleaching on the Great Barrier Reef now at \'catastrophic ...", "url": "https://www.sydney.edu.au/news-opinion/news/2025/01/21/coral-bleaching-2024-great-barrier-reef-one-tree-island.html", "content": "As the Great Barrier Reef faces increasing threats from climate change, the study calls for a collaborative approach to conservation that involves local communities, scientists and policymakers. Dr Shawna Foo , a Sydney Horizon Fellow and co-author of the study, said: \\"Seeing the impacts on a reef that has largely avoided mass bleaching until", "score": 0.3759361, "raw_content": null}, {"title": "Great Barrier Reef Outlook Report 2024: An ecosystem under pressure", "url": "https://icriforum.org/gbr-outlook-report-2024/", "content": "The 2024 Great Barrier Reef Outlook Report is the fourth in a series of comprehensive five-yearly reports on the Reef\'s health, pressures, management, and potential future. It found climate-driven threats such as warming oceans and severe cyclones have been compounding other impacts from crown-of-thorns starfish outbreaks, poor water quality", "score": 0.34634283, "raw_content": null}, {"title": "UNESCO expresses \'utmost concern\' at the state of the Great Barrier Reef", "url": "https://theconversation.com/unesco-expresses-utmost-concern-at-the-state-of-the-great-barrier-reef-257638", "content": "This 2017 photo from Ribbon Reef, near Cairns, shows what a healthy reef looks like. J Summerling/AP Poor water quality persists. Poor water quality is a major issue on the Great Barrier Reef.", "score": 0.31069487, "raw_content": null}, {"title": "Reef health updates | Reef Authority - gbrmpa", "url": "https://www2.gbrmpa.gov.au/learn/reef-health/reef-health-updates", "content": "As the lead managers of the Great Barrier Reef, the Reef Authority keeps an eye on the Reef year-round — with efforts stepped up over summer, a typically high-risk period from extreme weather. The Reef Authority releases updates on the health of Reef which includes; sea surface temperatures, rainfall and floods, cyclones, crown-of-thorns", "score": 0.18051112, "raw_content": null}], "response_time": 2.07}', name='tavily_search', id='cbf7ae84-1df7-4ead-b00d-f8fba2152720', tool_call_id='call_W37BFkNuZlJu9US1Tl71xpiX'),
AIMessage(content='The current conservation status of the Great Barrier Reef is concerning. The reef is facing significant threats primarily due to climate change, which is causing marine heatwaves and coral bleaching. A report highlights that while there have been some local efforts in conservation, such as catchment restoration to reduce sediment flow, these cannot keep pace with the destruction caused by climate impacts. Recent findings from the 2024 Great Barrier Reef Outlook Report indicate that climate-driven phenomena like warming oceans and severe cyclones are exacerbating other pressures, such as crown-of-thorns starfish outbreaks and poor water quality.\n\nSome reports have indicated that coral cover has increased in certain regions of the reef, but overall, the health of the reef remains in serious decline. There’s an urgent call for more funding and collaborative efforts between local communities, scientists, and policymakers to enhance conservation measures.\n\nFor more detailed information, you can refer to these articles:\n- [The Great Barrier Reef: Current Conservation Efforts and Future Outlook](https://discoverwildscience.com/the-great-barrier-reef-current-conservation-efforts-and-future-outlook-1-279446/)\n- [Great Barrier Reef Outlook Report 2024: An ecosystem under pressure](https://icriforum.org/gbr-outlook-report-2024/)', additional_kwargs={'refusal': None}, response_metadata={'token_usage': {'completion_tokens': 255, 'prompt_tokens': 2208, 'total_tokens': 2463, 'completion_tokens_details': {'accepted_prediction_tokens': 0, 'audio_tokens': 0, 'reasoning_tokens': 0, 'rejected_prediction_tokens': 0}, 'prompt_tokens_details': {'audio_tokens': 0, 'cached_tokens': 0}}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_34a54ae93c', 'id': 'chatcmpl-BjsVAxeGL7PKGVkb2DieFPE0ZPgor', 'service_tier': 'default', 'finish_reason': 'stop', 'logprobs': None}, id='run--71441b27-81a0-427f-8784-b2ea674bebd4-0', usage_metadata={'input_tokens': 2208, 'output_tokens': 255, 'total_tokens': 2463, 'input_token_details': {'audio': 0, 'cache_read': 0}, 'output_token_details': {'audio': 0, 'reasoning': 0}})]}
对话式回应
因为我们的提示包含一个聊天历史消息的占位符，所以我们的代理也可以考虑之前的交互，并像标准聊天机器人一样进行对话式回应
from langchain_core.messages import AIMessage, HumanMessage
agent.invoke(
{
"messages": [
HumanMessage(content="I'm Nemo!"),
AIMessage(content="Hello Nemo! How can I assist you today?"),
HumanMessage(content="What is my name?"),
],
}
)
API 参考:AIMessage | HumanMessage
{'messages': [HumanMessage(content="I'm Nemo!", additional_kwargs={}, response_metadata={}, id='8a67dea0-acd8-40f9-8c28-292c5f81c05f'),
AIMessage(content='Hello Nemo! How can I assist you today?', additional_kwargs={}, response_metadata={}, id='92a2533e-5c62-4cbe-80f1-302f5f1caf28'),
HumanMessage(content='What is my name?', additional_kwargs={}, response_metadata={}, id='efa8c3d3-86d7-428f-985e-a3aadd6504bc'),
AIMessage(content='Your name is Nemo!', additional_kwargs={'refusal': None}, response_metadata={'token_usage': {'completion_tokens': 6, 'prompt_tokens': 818, 'total_tokens': 824, 'completion_tokens_details': {'accepted_prediction_tokens': 0, 'audio_tokens': 0, 'reasoning_tokens': 0, 'rejected_prediction_tokens': 0}, 'prompt_tokens_details': {'audio_tokens': 0, 'cached_tokens': 0}}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_34a54ae93c', 'id': 'chatcmpl-BjsVIf5MX5jXUEjYCorT5bWYzc7iu', 'service_tier': 'default', 'finish_reason': 'stop', 'logprobs': None}, id='run--a1a32c7d-8066-4954-86f9-3a8f43fcb48d-0', usage_metadata={'input_tokens': 818, 'output_tokens': 6, 'total_tokens': 824, 'input_token_details': {'audio': 0, 'cache_read': 0}, 'output_token_details': {'audio': 0, 'reasoning': 0}})]}
如果需要，您还可以为 LangGraph 代理添加记忆功能来管理消息历史。让我们这样重新声明它
from langgraph.checkpoint.memory import MemorySaver
memory = MemorySaver()
agent = create_react_agent(model, tools, prompt=prompt, checkpointer=memory)
API 参考：MemorySaver
agent.invoke(
{"messages": [HumanMessage("I'm Nemo!")]},
config={"configurable": {"thread_id": "1"}},
)
{'messages': [HumanMessage(content="I'm Nemo!", additional_kwargs={}, response_metadata={}, id='31c2249a-13eb-4040-b56d-0c8746fa158e'),
AIMessage(content='Hello, Nemo! How can I assist you today?', additional_kwargs={'refusal': None}, response_metadata={'token_usage': {'completion_tokens': 12, 'prompt_tokens': 795, 'total_tokens': 807, 'completion_tokens_details': {'accepted_prediction_tokens': 0, 'audio_tokens': 0, 'reasoning_tokens': 0, 'rejected_prediction_tokens': 0}, 'prompt_tokens_details': {'audio_tokens': 0, 'cached_tokens': 0}}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_34a54ae93c', 'id': 'chatcmpl-BjsVRB0FItvtPawTTIAjNwgmlQFFw', 'service_tier': 'default', 'finish_reason': 'stop', 'logprobs': None}, id='run--a9703ca1-de4c-4f76-b622-9683d86ca777-0', usage_metadata={'input_tokens': 795, 'output_tokens': 12, 'total_tokens': 807, 'input_token_details': {'audio': 0, 'cache_read': 0}, 'output_token_details': {'audio': 0, 'reasoning': 0}})]}
然后如果我们重新运行我们的封装代理执行器
agent.invoke(
{"messages": [HumanMessage("What is my name?")]},
config={"configurable": {"thread_id": "1"}},
)
{'messages': [HumanMessage(content="I'm Nemo!", additional_kwargs={}, response_metadata={}, id='31c2249a-13eb-4040-b56d-0c8746fa158e'),
AIMessage(content='Hello, Nemo! How can I assist you today?', additional_kwargs={'refusal': None}, response_metadata={'token_usage': {'completion_tokens': 12, 'prompt_tokens': 795, 'total_tokens': 807, 'completion_tokens_details': {'accepted_prediction_tokens': 0, 'audio_tokens': 0, 'reasoning_tokens': 0, 'rejected_prediction_tokens': 0}, 'prompt_tokens_details': {'audio_tokens': 0, 'cached_tokens': 0}}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_34a54ae93c', 'id': 'chatcmpl-BjsVRB0FItvtPawTTIAjNwgmlQFFw', 'service_tier': 'default', 'finish_reason': 'stop', 'logprobs': None}, id='run--a9703ca1-de4c-4f76-b622-9683d86ca777-0', usage_metadata={'input_tokens': 795, 'output_tokens': 12, 'total_tokens': 807, 'input_token_details': {'audio': 0, 'cache_read': 0}, 'output_token_details': {'audio': 0, 'reasoning': 0}}),
HumanMessage(content='What is my name?', additional_kwargs={}, response_metadata={}, id='0cde6457-8d4d-45d5-b175-ad846018c4d2'),
AIMessage(content='Your name is Nemo! How can I help you today, Nemo?', additional_kwargs={'refusal': None}, response_metadata={'token_usage': {'completion_tokens': 15, 'prompt_tokens': 819, 'total_tokens': 834, 'completion_tokens_details': {'accepted_prediction_tokens': 0, 'audio_tokens': 0, 'reasoning_tokens': 0, 'rejected_prediction_tokens': 0}, 'prompt_tokens_details': {'audio_tokens': 0, 'cached_tokens': 0}}, 'model_name': 'gpt-4o-mini-2024-07-18', 'system_fingerprint': 'fp_34a54ae93c', 'id': 'chatcmpl-BjsVTa1plxGPNitbOcw7YVTFdmz1e', 'service_tier': 'default', 'finish_reason': 'stop', 'logprobs': None}, id='run--1d742bc1-5839-4837-b6f4-9a6b92fa6897-0', usage_metadata={'input_tokens': 819, 'output_tokens': 15, 'total_tokens': 834, 'input_token_details': {'audio': 0, 'cache_read': 0}, 'output_token_details': {'audio': 0, 'reasoning': 0}})]}
此 LangSmith 跟踪 显示了幕后发生的事情。
进一步阅读
有关如何构建代理的更多信息，请查看这些 LangGraph 指南
有关工具用法的更多信息，您还可以查看此用例部分。