Structured output

Minimal code

These examples use reasoning_effort: "none" so the selected model can enforce the schema without generating reasoning first. Choose a model that supports JSON output and disabling reasoning. A model that is temporarily paused is reported in GET /v1/models and on its model page.

curl https://api.runinfra.ai/v1/chat/completions \
  -H "Authorization: Bearer $RUNINFRA_GATEWAY_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "MODEL_ID",
    "messages": [
      {"role":"system","content":"Extract the receipt fields."},
      {"role":"user","content":"I bought coffee and a muffin at Blue Bottle on 2026-04-20 for $12.50"}
    ],
    "reasoning_effort": "none",
    "response_format": {
      "type": "json_schema",
      "json_schema": {
        "name": "receipt",
        "strict": true,
        "schema": {
          "type": "object",
          "properties": {
            "merchant":  {"type":"string"},
            "total_usd": {"type":"number"},
            "date":      {"type":"string"},
            "items":     {"type":"array","items":{"type":"string"}}
          },
          "required": ["merchant","total_usd","date","items"],
          "additionalProperties": false
        }
      }
    }
  }'

The SDK parse() helpers validate the reply against your Pydantic or Zod model. The curl tab shows the raw response_format request underneath them, which is the portable form for any client.

Which model, and what it needs

On some models, the gateway applies reasoning_effort: "none" when you omit it beside a schema. The model-specific source reference identifies the affected models; this exception is not a discovery field. The response header X-RunInfra-Reasoning-Effort-Applied reports the effort applied when the request did not name one.

If you explicitly send an incompatible effort, the request is refused with 400, param: "response_format". Read Chat completions for model-specific behavior.

What to tune

Common mistakes

• Asking for JSON in the prompt instead of in response_format. The model can still add commentary or markdown fences. Pass the field.
• Leaving additionalProperties open. Without additionalProperties: false, the reply may carry keys you did not declare. The helpers set it. Raw JSON Schema users must add it.
• Nested anyOf without discriminators. Use enums or discriminated unions. An unbounded anyOf gives the schema too little shape to enforce.
• Expecting enums to be case-insensitive. Schema enums are exact match. "Paris" does not satisfy enum: ["paris", "berlin"].

Next steps