API Breaking Change Check for OpenAPI — skill file for AI agents (AISkills402)

Overview

Compares two versions of one API description (OpenAPI 3.0 or 3.1 in YAML or JSON, or two JSON Schemas of one request or response) and lists ONLY the changes that break clients written against the old version, one line each with a fixed code, the place, old and new, and who breaks - or exactly No breaking changes. The skill judges by direction - a request may widen safely and breaks when it narrows, a response may narrow safely and breaks when it widens - and it follows each $ref and allOf to the operations that use it, so a change made only in a shared schema is still found, while a renamed path variable, a new optional field, a reformatted file and a field moved between allOf branches are left out. Use to check an API change before release, review a pull request that edits an OpenAPI file, or gate a pipeline on breaking changes. One-time purchase of the SKILL.md file itself (Agent Skills format), not an API call: $0.03 USDC on Base over x402, yours forever incl. free re-downloads and new versions. No account, no API key. Tested with a strong and a weak model; the card tells you where the weak one fails: https://aiskills402.com/skills/api-breaking-change-check

Health