【AI】PythonでOpenAI Function Callingを実装する方法

pip install openai

export OPENAI_API_KEY="your_api_key"

def get_weather(city: str) -> str:
    # 本来は天気APIを呼び出す処理を書く
    return f"{city}は晴れ、気温は25度です。"


tools = [
    {
        "type": "function",
        "function": {
            "name": "get_weather",
            "description": "指定した都市の現在の天気を取得する",
            "parameters": {
                "type": "object",
                "properties": {
                    "city": {
                        "type": "string",
                        "description": "天気を調べたい都市名"
                    }
                },
                "required": ["city"]
            }
        }
    }
]

from openai import OpenAI

client = OpenAI()

messages = [{"role": "user", "content": "東京の天気を教えて"}]

response = client.chat.completions.create(
    model="gpt-4o-mini",
    messages=messages,
    tools=tools,
    tool_choice="auto"
)

message = response.choices[0].message

import json

if message.tool_calls:
    messages.append(message)

    for tool_call in message.tool_calls:
        if tool_call.function.name == "get_weather":
            args = json.loads(tool_call.function.arguments)
            result = get_weather(args["city"])

            messages.append({
                "role": "tool",
                "tool_call_id": tool_call.id,
                "content": result
            })

second_response = client.chat.completions.create(
    model="gpt-4o-mini",
    messages=messages
)

print(second_response.choices[0].message.content)