| name | api-designer |
| description | Designs RESTful APIs with endpoint naming, versioning strategies (URL path, header-based), pagination (offset and cursor), error response schemas, and OpenAPI conventions. Use when the user asks about REST API design, creating endpoints, URL structure, API versioning, status codes, Swagger, or OpenAPI specs. |
| autoInvoke | false |
| priority | medium |
| triggers | ["API design","REST API","endpoint design"] |
| user-invocable | false |
AI-consumed reference. Optimized for Claude to read during execution.
Human-readable explanation: see docs/architecture/HIERARCHICAL_PLANNING.md
or docs/getting-started/ depending on topic.
Skill: API Designer
Design consistent, RESTful APIs with versioning, documentation, and error handling.
RESTful Conventions
| Method | Endpoint | Purpose | Response |
|---|
| GET | /users | List | 200 + array |
| GET | /users/:id | Get one | 200 / 404 |
| POST | /users | Create | 201 + created |
| PUT | /users/:id | Replace | 200 / 404 |
| PATCH | /users/:id | Update | 200 / 404 |
| DELETE | /users/:id | Delete | 204 / 404 |
Nested: GET /users/:userId/orders
Naming
- Resources: plural nouns (
/users, /orders)
- Query params: snake_case (
page_size)
- Request/Response bodies: camelCase
Versioning: URL path /api/v1/... (recommended).
Response Format
Success: { "data": {...}, "meta": {...} }
List: Add meta: { page, pageSize, total, totalPages }
Error: { "error": { "code": "VALIDATION_ERROR", "message": "...", "fields": {...} } }
Status Codes
| Code | When |
|---|
| 200 | Successful GET/PUT/PATCH |
| 201 | Successful POST |
| 204 | Successful DELETE |
| 400/422 | Invalid input / validation |
| 401/403 | No auth / no permission |
| 404/409 | Not found / conflict |
| 429 | Rate limited |
| 500 | Unexpected error |
Pagination
Offset: ?page=2&page_size=20 (simple, slow on large sets)
Cursor: ?cursor=abc&limit=20 (consistent, fast, no page jump)
Filtering & Sorting
GET /users?status=active&sort=created_at:desc&q=john&page=1&page_size=20
Design Workflow
- Define resources and relationships → 2. Choose versioning strategy → 3. Define endpoints with RESTful naming → 4. Specify response/error schemas → 5. Add pagination, filtering, sorting → 6. Document with OpenAPI → 7. Add rate limiting headers
Checklist
RESTful naming, consistent response format, proper status codes, pagination for lists, error codes, versioning, OpenAPI docs, rate limiting headers.
Related Rules
rules/agent/api-design-rules.md — enforcement checklist (short form of this skill)rules/core/simplicity-over-complexity.md — favor flat resources over nested hierarchies, reject premature GraphQL when REST fits, no speculative "future-proofing" fieldsrules/agent/structured-data-schema.md — consistent schema across endpointsrules/agent/error-handling-standard.md — uniform error envelope
