開放式模型的函式呼叫

函式呼叫功能可讓模型判斷何時應叫用外部工具或 API，然後生成結構化資料，其中包含執行作業所需的函式和引數。Vertex AI 模型即服務 (MaaS) 提供的所有開放原始碼模型都支援函式呼叫。

如要進一步瞭解函式呼叫功能的概念資訊，請參閱「函式呼叫簡介」。

使用函式呼叫

下列用途是整合外部氣象 API，用來查看特定地點的目前天氣。這段程式碼使用 REST 呼叫，透過 get_current_weather 函式比較兩個城市的氣象，該函式是在 tools 內的結構定義中宣告。

{
  "model": "MODEL_NAME",
  "messages": [
    {
      "role": "user",
      "content": "Which city has a higher temperature, Boston or new Delhi, and by how much in F?"
    }
  ],
  "tools": [
    {
      "type": "function",
      "function": {
        "name": "get_current_weather",
        "description": "Get the current weather in a given location",
        "parameters": {
          "type": "object",
          "properties": {
            "location": {
              "type": "string",
              "description": "The city and state, e.g. San Francisco, CA"
            },
            "unit": {
              "type": "string",
              "enum": ["celsius", "fahrenheit"]
            }
          },
          "required": ["location"]
        }
      }
    }
  ],
  "tool_choice": "auto"
}

收到要求後，模型會判斷需要 get_current_weather 函式的輸出內容，並在 tool_calls 中提供必要的函式和引數。

函式呼叫，用於擷取波士頓的天氣：

{"function":{"arguments":"{\"location\":\"Boston, MA\",\"unit\":\"fahrenheit\"}","name":"get_current_weather"} "id":"get_current_weather","type":"function"}

函式呼叫，用於擷取新德里的天氣：

{"function":{"arguments":"{\"location\":\"New Delhi, India\",\"unit\":\"fahrenheit\"}","name":"get_current_weather"},"id":"get_current_weather","type":"function"}

詳細範例

延續上一個範例，以下是使用 get_current_weather 函式擷取氣象資訊後，您可能會得到的完整輸出內容。

{
  "model": "MODEL_NAME",
  "messages": [
    {
      "role": "user",
      "content": "Which city has a higher temperature, Boston or new Delhi and by how much in F?"
    },
    {
      "role": "assistant",
      "content": "I'll check the current temperatures for Boston and New Delhi in Fahrenheit and compare them. I'll call the weather function for both cities.",
      "tool_calls": [{"function":{"arguments":"{\"location\":\"Boston, MA\",\"unit\":\"fahrenheit\"}","name":"get_current_weather"},"id":"get_current_weather","type":"function"},{"function":{"arguments":"{\"location\":\"New Delhi, India\",\"unit\":\"fahrenheit\"}","name":"get_current_weather"},"id":"get_current_weather","type":"function"}]
    },
    {
      "role": "tool",
      "content": "The temperature in Boston is 75 degrees Fahrenheit.",
      "tool_call_id": "get_weather"
    },
    {
      "role": "tool",
      "content": "The temperature in New Delhi is 50 degrees Fahrenheit.",
      "tool_call_id": "get_weather"
    }
  ],
  "tools": [
    {
      "type": "function",
      "function": {
        "name": "get_current_weather",
        "description": "Get the current weather in a given location",
        "parameters": {
          "type": "object",
          "properties": {
            "location": {
              "type": "string",
              "description": "The city and state, e.g. San Francisco, CA"
            },
            "unit": {
              "type": "string",
              "enum": ["celsius", "fahrenheit"]
            }
          },
          "required": ["location"]
        }
      }
    }
  ],
  "tool_choice": "auto"
}

收到透過呼叫外部 get_current_weather 函式擷取的資訊後，模型可以綜合兩項 tool 回應中的資訊，回答使用者的問題。

以下是模型輸出內容的範例：

{
 "choices": [
  {
   "finish_reason": "stop",
   "index": 0,
   "logprobs": null,
   "message": {
    "content": "Based on the current weather data:\n\n- **Boston, MA**: 75°F 
    \n- **New Delhi, India**: 50°F  \n\n**Comparison**:
    \nBoston is **25°F warmer** than New Delhi.  \n\n**Answer**:
    \nBoston has a higher temperature than New Delhi by 25 degrees Fahrenheit.",
    "role": "assistant"
   }
  }
 ],
 "created": 1750450289,
 "id": "2025-06-20|13:11:29.240295-07|6.230.75.101|-987540014",
 "model": "MODEL_NAME",
 "object": "chat.completion",
 "system_fingerprint": "",
 "usage": {
  "completion_tokens": 66,
  "prompt_tokens": 217,
  "total_tokens": 283
 }
}