Engineering Structured Output Output Validation

Validate Structured Output from AI

Fields checked against the contract: missing ones flagged, invented ones caught, prose around the object detected.

Overview

Structured output drifts in three ways: fields go missing, fields get invented, and prose creeps in around the object. This setup validates an extraction response that does all three at a typical scale — a friendly "Sure! Here is the extracted data:" preamble, a missing timeline field, and an invented notes field. The validator separates them by severity (missing = FAIL, invented = WARN, prose = WARN), and the repair prompt addresses each one specifically, including the null-over-invention rule for the missing field.

How to use this resource

  1. Reuse your generator's field list

    The fields you defined in the extraction prompt are exactly the expected structure here.

  2. Mind the severity split

    Missing fields fail; invented fields warn — your pipeline may tolerate extras but never absences.

  3. Repair with null discipline

    The repair prompt says "use null if the value is unknown — never invent one"; the fix doesn't become a new violation.

Why This Works

  • Field-set comparison catches both directions of drift
  • Severity weighting mirrors real consumer tolerance
  • The null-over-invention repair rule closes the loop the contract opened

Best for

  • Extraction pipelines with downstream consumers
  • Outputs that must match a field list exactly
  • Debugging "where did this field come from?" incidents

Not for

  • Defining the extraction fields — that's the Extraction Prompt Generator
  • Checking whether extracted values are TRUE — structure validation, not fact-checking

Use cases

  • Auditing extraction output before it enters the CRM
  • Catching invented fields that schema-less checks miss
  • Stripping conversational wrapping from data responses

FAQ

Why is a missing field treated more seriously than an extra field in this validator?

The severity split weights them differently: the missing "timeline" field is a FAIL while the invented "notes" field is only a WARN. A consumer reading the six expected fields can usually ignore an extra key, but a downstream absence breaks it. The REPAIR TASK flags both directions and gives a specific fix for each; you decide which one blocks your pipeline.

Does the repair prompt fix a missing field by making up a value for it?

It fixes the absence without inventing content. The rule for the missing "timeline" reads "include timeline; use null if the value is unknown — never invent one," so the repair adds the key with null rather than a guessed date. That keeps the correction from becoming a second violation. You paste the repaired output back into your own assistant.

What does the ai output validator hand back when it runs this?

A REPAIR TASK prompt listing the problems it found — prose outside the JSON, the missing "timeline", the unexpected "notes" — each with a specific fix. The validator surfaces and packages the issues; it does not re-run your model or promise it caught every drift. You paste that repair prompt back to the assistant that produced the bad output.

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