Skip to main content Designs REST and GraphQL APIs including endpoints, error handling, versioning, and documentation. Use when creating new APIs, designing endpoints, reviewing API contracts, or when asked about REST, GraphQL, or API patterns.
npx skills add cloudai-x/claude-workflow-v2 --skill designing-apis agent-skills ai ai-agents claude-code codex cursor
Designing APIs
When to Load
Trigger : Designing REST or GraphQL endpoints, API contracts, versioning, request/response formats
Skip : Internal-only code with no API surface
API Design Workflow
Copy this checklist and track progress:
API Design Progress:
- [ ] Step 1: Define resources and relationships
- [ ] Step 2: Design endpoint structure
- [ ] Step 3: Define request/response formats
- [ ] Step 4: Plan error handling
- [ ] Step 5: Add authentication/authorization
- [ ] Step 6: Document with OpenAPI spec
- [ ] Step 7: Validate design against checklist
REST API Design
URL Structure
# Resource-based URLs (nouns, not verbs)
GET /users # List users
GET /users/:id # Get user
POST /users # Create user
PUT /users/:id # Replace user
PATCH /users/:id # Update user
DELETE /users/:id # Delete user
# Nested resources
GET /users/:id/orders # User's orders
POST /users/:id/orders # Create order for user
# Query parameters for filtering/pagination
GET /users?role=admin&status=active
GET /users?page=2&limit=20&sort=-createdAt
HTTP Status Codes
Code Meaning Use Case 200 OK Successful GET, PUT, PATCH 201 Created Successful POST 204 No Content Successful DELETE 400 Bad Request Invalid input 401 Unauthorized Missing/invalid auth 403 Forbidden Valid auth, no permission 404 Not Found Resource doesn't exist 409 Conflict Duplicate, state conflict 422 Unprocessable Validation failed 429 Too Many Requests Rate limited 500 Internal Error Server error
Response Formats {
"data": {
"id": "123",
"type": "user",
"attributes": {
"name": "John Doe",
"email": "[email protected] "
}
},
"meta": {
"requestId": "abc-123"
}
}
List Response with Pagination:
{
"data": [...],
"meta": {
"total": 100,
"page": 1,
"limit": 20,
"totalPages": 5
},
"links": {
"self": "/users?page=1",
"next": "/users?page=2",
"last": "/users?page=5"
}
}
{
"error": {
"code": "VALIDATION_ERROR",
"message": "Invalid input data",
"details": [
{
"field": "email",
"message": "Must be a valid email address"
}
]
},
"meta": {
"requestId": "abc-123"
}
}
API Versioning URL Versioning (Recommended):
/api/v1/users
/api/v2/users
Accept: application/vnd.api+json; version=1
Authentication Patterns Authorization: Bearer eyJhbGciOiJIUzI1NiIs...
Rate Limiting Headers X-RateLimit-Limit: 100
X-RateLimit-Remaining: 95
X-RateLimit-Reset: 1609459200
Retry-After: 60
GraphQL Patterns type Query {
user(id: ID!): User
users(filter: UserFilter, pagination: Pagination): UserConnection!
}
type Mutation {
createUser(input: CreateUserInput!): UserPayload!
updateUser(id: ID!, input: UpdateUserInput!): UserPayload!
}
type User {
id: ID!
name: String!
email: String!
orders(first: Int, after: String): OrderConnection!
}
input CreateUserInput {
name: String!
email: String!
}
type UserPayload {
user: User
errors: [Error!]
}
OpenAPI Specification Template
API Design Validation After completing the design, validate against this checklist:
Validation Checklist:
- [ ] All endpoints use nouns, not verbs
- [ ] HTTP methods match operations correctly
- [ ] Consistent response format across endpoints
- [ ] Error responses include actionable details
- [ ] Pagination implemented for list endpoints
- [ ] Authentication defined for protected endpoints
- [ ] Rate limiting headers documented
- [ ] OpenAPI spec is complete and valid
If validation fails, return to the relevant design step and address the issues.
Security Checklist Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Set up and use 1Password CLI (op). Use when installing the CLI, enabling desktop app integration, signing in (single or multi-account), or reading/injecting/running secrets via op.
CLI to manage emails via IMAP/SMTP. Use `himalaya` to list, read, write, reply, forward, search, and organize emails from the terminal. Supports multiple accounts and message composition with MML (MIME Meta Language).
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Set up and use 1Password CLI (op). Use when installing the CLI, enabling desktop app integration, signing in (single or multi-account), or reading/injecting/running secrets via op.
CLI to manage emails via IMAP/SMTP. Use `himalaya` to list, read, write, reply, forward, search, and organize emails from the terminal. Supports multiple accounts and message composition with MML (MIME Meta Language).