xoai/api
tools/sage-claude-plugin/skills/api/SKILL.md
Corrects the 13 most common API design mistakes agents make — grounded in Geewax, Amundsen, Ousterhout, Kleppmann, and Gough/Bryant
$ install --global
skillsauthnpx skillsauth add xoai/sage apiInstall this skill globally with one command. Works with Claude Code, Cursor, and Windsurf.
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SKILL.md
- name:
- api
- description:
- Corrects the 13 most common API design mistakes agents make — grounded in Geewax, Amundsen, Ousterhout, Kleppmann, and Gough/Bryant
- version:
- 2.0.0
- type:
- knowledge
- layer:
- domain
- sage:
- >=1.0.0
- detected:
- [express, fastify, koa, hono, django, flask, rails, spring, gin, echo, actix-web, axum]
- tags:
- [express,fastify,koa,hono,django]
api
Layer 1 — Domain Foundation (v2.0)
Corrects the 13 most common API design mistakes agents make, grounded in 5 authoritative sources:
- Geewax (API Design Patterns) — cursor pagination, error structure, idempotency, request deduplication
- Amundsen (RESTful Web API Cookbook) — PUT for idempotent creates, HTTP method semantics
- Ousterhout (Philosophy of Software Design) — information hiding, define errors out of existence, different layer/different abstraction
- Kleppmann (Designing Data-Intensive Applications) — network failures are normal, batch processing, data integrity
- Gough/Bryant (Mastering API Architecture) — schema validation, API lifecycle, backward compatibility, deprecation
What's Included
| Type | Count | Coverage | |------|-------|----------| | Patterns | 13 | Error envelope, input validation, cursor pagination, batch queries, auth-first, URL conventions, rate limiting, idempotent writes, separate representation, versioning, HTTP status codes, structured logging, health endpoints | | Anti-patterns | 9 | Inconsistent errors, trusting input, returning all records, N+1 loops, bolt-on auth, non-idempotent creates, leaking DB internals, 200-with-error-body, no versioning plan | | Constitution | 11 | principles |
Every pattern includes code examples showing wrong vs right approaches. Every anti-pattern includes root cause explaining WHY agents default to the wrong behavior.
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