API Design Review

A review skill for HTTP API endpoints that checks design consistency, input handling, and error communication.

What it covers

Endpoint design — RESTful resource naming, proper HTTP method usage, consistent URL structure
Input validation — schema validation at the boundary, rejecting unknown fields, type coercion risks
Status codes — correct usage of 2xx/4xx/5xx, distinguishing 400 from 422, never returning 200 for errors
Pagination and filtering — cursor vs. offset pagination, consistent query parameter patterns
Rate limiting and auth — rate limit headers, proper 401 vs. 403 usage, API key handling
Error responses — structured error bodies, actionable error messages, no stack traces in production

Run this when building or modifying API endpoints, especially before publishing APIs that external consumers will depend on.