Structured Output Validation - Phaseo Docs

Even with schema-constrained generation, always validate output on your server.

Recommended loop

Request schema-constrained output.
Parse JSON.
Validate against your server schema.
Retry once with a corrective prompt if invalid.
Fallback to safe failure if still invalid.

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);
}

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.

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 July 26, 2026