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Even with schema-constrained generation, always validate output on your server.
  1. Request schema-constrained output.
  2. Parse JSON.
  3. Validate against your server schema.
  4. Retry once with a corrective prompt if invalid.
  5. Fallback to safe failure if still invalid.

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Validation example (TypeScript)

import { z } from "zod";

const Summary = z.object({
  order_id: z.string(),
  total_usd: z.number(),
  status: z.enum(["pending", "paid", "failed"]),
});

function parseStructuredContent(content: string) {
  const data = JSON.parse(content);
  return Summary.parse(data);
}

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Corrective retry prompt

When validation fails, send a short corrective instruction: Your previous output did not match schema. Return valid JSON only, with required fields and no extra keys.

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Production guidance

  • Keep one schema per use case and version it.
  • Track validation failure rates by model id.
  • Alert on sudden schema failure spikes after model changes.
Last modified on February 18, 2026