API Documenter

Specialist in creating comprehensive API documentation using OpenAPI/Swagger specifications.

When This Skill Activates

Activates when you:

• Ask to document an API
• Create OpenAPI/Swagger specs
• Need API reference documentation
• Mention "API docs"

OpenAPI Specification Structure

openapi: 3.0.3
info:
  title: API Title
  version: 1.0.0
  description: API description
servers:
  - url: https://example.com/api/v1
paths:
  /users:
    get:
      summary: List users
      operationId: listUsers
      tags:
        - users
      parameters: []
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/User'
components:
  schemas:
    User:
      type: object
      properties:
        id:
          type: string
        name:
          type: string

Endpoint Documentation

For each endpoint, document:

Required Fields

• summary: Brief description
• operationId: Unique identifier
• description: Detailed explanation
• tags: For grouping
• responses: All possible responses

Recommended Fields

• parameters: All parameters with details
• requestBody: For POST/PUT/PATCH
• security: Authentication requirements
• deprecated: If applicable

Example

/users/{id}:
  get:
    summary: Get a user by ID
    operationId: getUserById
    description: Retrieves a single user by their unique identifier
    tags:
      - users
    parameters:
      - name: id
        in: path
        required: true
        schema:
          type: string
        description: The user ID
    responses:
      '200':
        description: User found
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/User'
      '404':
        description: User not found
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Error'

Schema Documentation

Best Practices

1. Use references for shared schemas
2. Add descriptions to all properties
3. Specify format for strings (email, uuid, date-time)
4. Add examples for complex schemas
5. Mark required fields

Example

components:
  schemas:
    User:
      type: object
      required:
        - id
        - email
      properties:
        id:
          type: string
          format: uuid
          description: Unique user identifier
          example: "550e8400-e29b-41d4-a716-446655440000"
        email:
          type: string
          format: email
          description: User's email address
          example: "user@example.com"
        createdAt:
          type: string
          format: date-time
          description: Account creation timestamp

Authentication Documentation

Document auth requirements:

security:
  - bearerAuth: []

components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT
      description: Use your JWT token from /auth/login

Error Responses

Standard error format:

components:
  schemas:
    Error:
      type: object
      properties:
        error:
          type: string
          description: Error message
        code:
          type: string
          description: Application-specific error code
        details:
          type: object
          description: Additional error details

Common HTTP status codes:

• 200: Success
• 201: Created
• 204: No Content
• 400: Bad Request
• 401: Unauthorized
• 403: Forbidden
• 404: Not Found
• 409: Conflict
• 422: Unprocessable Entity
• 500: Internal Server Error

Scripts

Generate OpenAPI spec from code:

python scripts/generate_openapi.py

Validate OpenAPI spec:

python scripts/validate_openapi.py openapi.yaml

References

• references/openapi-template.yaml - OpenAPI template
• references/examples/ - API documentation examples
• OpenAPI Specification