AI Output JSON Schema Checker

This dependency-free, offline reporter checks one saved model-output JSON file against one local, explicit schema profile. It separates malformed or unreadable output from a valid document that fails schema rules. An optional local policy can normalize named fields; every change is logged by type and digest, and the transformed copy is checked again. Nothing is sent to a model or written back to disk.

This walkthrough uses the tool's public README and checked-in example files. Run the command from a repository checkout with Node.js 22+; inspect the source before using it on your own files.

Run the checked-in example

node bin/ai-output-json-schema-checker.mjs --root examples --schema record.schema.json --output good.output.json
node bin/ai-output-json-schema-checker.mjs --root examples --schema record.schema.json --output bad.output.json
node bin/ai-output-json-schema-checker.mjs --root examples --schema record.schema.json --output normalizable.output.json --normalization-policy normalization-policy.json
node bin/ai-output-json-schema-checker.mjs --root examples --schema record.schema.json --output good.output.json --report check.report.json
node bin/ai-output-json-schema-checker.mjs --help
npm run check

Read the result

The first, third and fourth checks exit 0; the second exits 1. Completed and incomplete checks emit one JSON report on stdout and a fixed, human-readable status and finding count on stderr. Add --json to suppress only that human report summary; invalid configuration still leaves stdout empty and emits a fixed diagnostic on stderr. --help alone prints usage and exits 0. The summary contains no input values or identifiers. Optional --report FILE writes the same JSON bytes to a named file under the declared root; without it, no file is written. Programmatic callers can import checkOutput, exitCodeFor, RULESEVERITY, and TOOLID from src/index.mjs. checkOutput accepts {root, schema, output, normalizationPolicy?, limits?, now?}; now is an injected clock function, defaulting to Date.now.

Where this check stops

This tool does not execute model calls, contact providers, infer a schema, implement full JSON Schema, attest to the truth of a model response, prove external approval, perform implicit coercion, or modify output documents. It validates only the saved evidence and profile described above.

Before adapting the command to your own workflow, review the accepted inputs, exit codes and safety boundaries in the README.

Compiled with AI assistance from checked-in public documentation and example scripts. Run the example and review the repository's current documentation before relying on its result.