Python LangChain 开发问题:TypeError: “Could not resolve authentication method. Expected either api_key
fromlangchain.agentsimportcreate_agentdefget_weather(city:str)->str:"""获取指定城市的天气"""returnf"{city}天气总是晴朗!"agent=create_agent(model="anthropic:claude-sonnet-4-5",tools=[get_weather],system_prompt="你是一个乐