单 Agent 应用：从目标拆解到受控工具执行

python -m pip install "langchain>=1,<2" "langchain-openai>=1,<2"
export OPENAI_API_KEY="replace-with-your-key"
export AGENT_MODEL="provider-model-name"

import os
from langchain.agents import create_agent
from langchain.tools import tool


@tool
def get_device_status(device_id: str) -> dict:
    """查询 AX 系列设备当前状态，只读。"""
    data = {"AX-3": {"online": False, "temperature": 38.2}}
    return data.get(device_id, {"error": "not_found"})


@tool
def get_inspection_rule(topic: str) -> dict:
    """查询巡检规则，只返回与 topic 相关的规则。"""
    rules = {"offline": "设备离线时通知值班人员检查网络，不自动创建工单。"}
    return {"rule": rules.get(topic, "现有规则无法确认")}


agent = create_agent(
    model=os.environ["AGENT_MODEL"],
    tools=[get_device_status, get_inspection_rule],
    system_prompt=(
        "你是只读巡检助手。先查询事实，再查询必要规则；"
        "不得声称已经创建工单，不得补充工具结果之外的设备事实。"
    ),
)

result = agent.invoke(
    {"messages": [{"role": "user", "content": "检查 AX-3 是否需要人工处理，并说明依据。"}]},
    config={"recursion_limit": 6, "tags": ["stage08", "single-agent"]},
)

print(result["messages"][-1].text)
for message in result["messages"]:
    print(type(message).__name__, getattr(message, "tool_calls", None))