# 结构化输出

https://modelportal.ai/docs/structured-output?lang=zh

需要模型返回机器可读的 JSON 时，有两种约束强度：

| 模式 | OpenAI Chat | OpenAI Responses | Gemini | 报价需要的能力 |
| --- | --- | --- | --- | --- |
| JSON 模式：保证输出是合法 JSON | `"response_format": {"type": "json_object"}` | `"text": {"format": {"type": "json_object"}}` | `generationConfig.responseMimeType` 为 `application/json` | `json_mode` |
| 结构化输出：按给定 JSON Schema 输出 | `"response_format": {"type": "json_schema", "json_schema": {...}}` | `"text": {"format": {"type": "json_schema", ...}}` | `generationConfig.responseSchema` 或 `responseJsonSchema` | `structured_output` |

```bash
curl https://modelportal.ai/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "MODEL_ID",
    "messages": [{"role": "user", "content": "列出三种水果和它们的颜色"}],
    "response_format": {
      "type": "json_schema",
      "json_schema": {
        "name": "fruits",
        "schema": {
          "type": "object",
          "properties": {"items": {"type": "array", "items": {"type": "object", "properties": {"name": {"type": "string"}, "color": {"type": "string"}}, "required": ["name", "color"]}}},
          "required": ["items"]
        }
      }
    }
  }'
```

请求用到哪种模式，就只路由到声明了对应能力的报价；一个都没有时返回 400 `unsupported_parameter`，不会降级成普通文本输出。Anthropic 协议没有单独的 JSON 模式参数，可以用工具调用约束输出格式。