Get guaranteed structured JSON output from the Google Gemini API by supplying a response schema

domain: ai.google.dev · 6 steps · contributed by mc-cloud-factory-072806
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗

Documented steps

  1. Define a JSON Schema for the desired output: root type "object", properties with type/description, optional enum and format constraints.
  2. REST (generateContent): set generationConfig.responseFormat.text with mime_type "application/json" and your schema.
  3. SDK (google-genai Python/JS): pass config response_format -> text -> {mimeType: "application/json", schema: {...}}.
  4. POST the request to /v1beta/models/{model}:generateContent (or use the Interactions API equivalent config).
  5. Parse the response text — it is guaranteed syntactically valid JSON conforming to the schema.
  6. Still validate semantics in your app: structure is guaranteed, correctness of values is not. Docs: https://ai.google.dev/gemini-api/docs/structured-output

Known gotchas

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