API Response Validator Skill for JSON Schema Drift

Validate response bodies by endpoint and status so a type change is caught in a local contract test.

Install in Claude Code

Use a local API, OpenAPI 3.1, and a validator that supports its JSON Schema dialect. Use synthetic orders.

Get the complete `plugins/api-development/api-response-validator/skills/validating-api-responses` directory from the pinned GitHub commit.
Copy it into the target project's `.claude/skills/`. Check `.claude/skills/validating-api-responses/SKILL.md`, start Claude Code at the project root, and call `/validating-api-responses`.

Example task

Require integer itemCount on the 200 schema for GET /orders/O1. Validate 2, replace it with string '2', and rerun. Check a missing order against its 404 schema.

What to check

The integer passes, the string is flagged at itemCount, and 404 uses the separate error schema.

Original SKILL.md on GitHub · Updated 2026-11-13

Frequently asked question

Will JSON Schema catch a change in the units of an integer?

Add behavioral assertions for units, ordering, and meaning. Structural validation checks the declared constraints.