借助函数调用，您可以定义自定义函数，并让 LLM 能够调用这些函数来检索实时信息或与外部系统（例如 SQL 数据库或客户服务工具）进行交互。
如需详细了解函数调用的概念性信息，请参阅函数调用简介。
使用函数调用
以下示例展示了如何使用函数调用。
Python
在尝试此示例之前，请按照《Vertex AI 快速入门：使用客户端库》中的 Python 设置说明执行操作。 如需了解详情，请参阅 Vertex AI Python API 参考文档。
如需向 Vertex AI 进行身份验证，请设置应用默认凭证。 如需了解详情，请参阅为本地开发环境设置身份验证。
在运行此示例之前，请务必设置 OPENAI_BASE_URL 环境变量。如需了解详情，请参阅身份验证和凭据。
from openai import OpenAI client = OpenAI() response = client.chat.completions.create( model="MODEL", messages=[ {"role": "user", "content": "CONTENT"} ], tools=[ { "type": "function", "function": { "name": "FUNCTION_NAME", "description": "FUNCTION_DESCRIPTION", "parameters": PARAMETERS_OBJECT, } } ], tool_choice="auto", )
- MODEL：您要使用的模型名称，例如
qwen/qwen3-next-80b-a3b-instruct-maas。 - CONTENT：要发送给模型的用户提示。
- FUNCTION_NAME：要调用的函数名称。
- FUNCTION_DESCRIPTION：函数的说明。
- PARAMETERS_OBJECT：用于定义函数参数的字典，例如：
{"type": "object", "properties": {"location": {"type": "string", "description": "The city and state"}}, "required": ["location"]}
REST
设置您的环境后，您可以使用 REST 测试文本提示。以下示例会向发布方模型端点发送请求。
在使用任何请求数据之前，请先进行以下替换：
- PROJECT_ID：您的 Google Cloud 项目 ID。
- LOCATION：支持开放模型的区域。
- MODEL：您要使用的模型名称，例如
qwen/qwen3-next-80b-a3b-instruct-maas。 - CONTENT：要发送给模型的用户提示。
- FUNCTION_NAME：要调用的函数名称。
- FUNCTION_DESCRIPTION：函数的说明。
- PARAMETERS_OBJECT：用于定义函数参数的 JSON 架构对象，例如：
{"type": "object", "properties": {"location": {"type": "string", "description": "The city and state"}}, "required": ["location"]}
HTTP 方法和网址：
POST https://LOCATION-aiplatform.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/endpoints/openapi/chat/completions
请求 JSON 正文：
{
"model": "MODEL",
"messages": [
{
"role": "user",
"content": "CONTENT"
}
],
"tools": [
{
"type": "function",
"function": {
"name": "FUNCTION_NAME",
"description": "FUNCTION_DESCRIPTION",
"parameters": PARAMETERS_OBJECT
}
}
],
"tool_choice": "auto"
}
如需发送请求，请选择以下方式之一：
curl
将请求正文保存在名为 request.json 的文件中，然后执行以下命令：
curl -X POST \
-H "Authorization: Bearer $(gcloud auth print-access-token)" \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
"https://LOCATION-aiplatform.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/endpoints/openapi/chat/completions"
PowerShell
将请求正文保存在名为 request.json 的文件中，然后执行以下命令：
$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }
Invoke-WebRequest `
-Method POST `
-Headers $headers `
-ContentType: "application/json; charset=utf-8" `
-InFile request.json `
-Uri "https://LOCATION-aiplatform.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/endpoints/openapi/chat/completions" | Select-Object -Expand Content
您应该会收到一个成功的状态代码 (2xx) 和一个空响应。
示例
下面显示了使用 get_current_weather 函数提取气象信息后可能获得的完整输出。
Python
from openai import OpenAI client = OpenAI() response = client.chat.completions.create( model="qwen/qwen3-next-80b-a3b-instruct-maas", 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_current_weather" }, { "role": "tool", "content": "The temperature in New Delhi is 50 degrees Fahrenheit.", "tool_call_id": "get_current_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" )
curl
curl -X POST \ -H "Authorization: Bearer $(gcloud auth print-access-token)" \ -H "Content-Type: application/json" \ https://us-central1-aiplatform.googleapis.com/v1/projects/sample-project/locations/us-central1/endpoints/openapi/chat/completions -d \ '{ "model": "qwen/qwen3-next-80b-a3b-instruct-maas", "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_current_weather" }, { "role": "tool", "content": "The temperature in New Delhi is 50 degrees Fahrenheit.", "tool_call_id": "get_current_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" }'
{ "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": "qwen/qwen3-next-80b-a3b-instruct-maas", "object": "chat.completion", "system_fingerprint": "", "usage": { "completion_tokens": 66, "prompt_tokens": 217, "total_tokens": 283 } }
特定于模型的指导
以下部分针对函数调用提供了特定于模型的指导。
DeepSeek
如果您使用系统提示，DeepSeek 模型在函数调用方面的表现会不太理想。为了获得最佳性能，请在使用 DeepSeek 模型进行函数调用时省略系统提示。
Llama
“meta/llama3-405b-instruct-maas”不支持 tool_choice = 'required'。
OpenAI
使用 openai/gpt-oss-120b-instruct-maas 和 openai/gpt-oss-20b-instruct-maas 时，请将工具定义放在系统提示中，以获得最佳性能。例如：
{"messages": [ {"role": "system", "content": "You are a helpful assistant with access to the following functions. Use them if required:\n..."}, {"role": "user", "content": "What's the weather like in Boston?"}, ... ]}
这些模型不支持 tool_choice = 'required' 或命名工具调用。
Qwen
当 tool_choice 明确设置为 auto 或 none 时，Qwen 模型的效果最佳。如果未设置 tool_choice，模型可能无法达到理想效果。