# API Documentation Generator

> Generate comprehensive, developer-friendly API documentation from code, including endpoints, parameters, examples, and best practices

- Skill: `diegosouzapw/api-documentation-generator-5` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add diegosouzapw/api-documentation-generator-5`
- Raw SKILL.md: https://api.skillmd.com/api/skills/diegosouzapw/api-documentation-generator-5/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Docs & Writing
- Author: diegosouzapw (https://skillmd.com/u/diegosouzapw)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/diegosouzapw/api-documentation-generator-5

---


# API Documentation Generator

## Overview

Automatically generate clear, comprehensive API documentation from your
codebase. This skill helps you create professional documentation that includes
endpoint descriptions, request/response examples, authentication details, error
handling, and usage guidelines.

Perfect for REST APIs, GraphQL APIs, and WebSocket APIs.

## When to Use This Skill

- Use when you need to document a new API
- Use when updating existing API documentation
- Use when your API lacks clear documentation
- Use when onboarding new developers to your API
- Use when preparing API documentation for external users
- Use when creating OpenAPI/Swagger specifications

## How It Works

### Step 1: Analyze the API Structure

First, I'll examine your API codebase to understand:

- Available endpoints and routes
- HTTP methods (GET, POST, PUT, DELETE, etc.)
- Request parameters and body structure
- Response formats and status codes
- Authentication and authorization requirements
- Error handling patterns

### Step 2: Generate Endpoint Documentation

For each endpoint, I'll create documentation including:

**Endpoint Details:**

- HTTP method and URL path
- Brief description of what it does
- Authentication requirements
- Rate limiting information (if applicable)

**Request Specification:**

- Path parameters
- Query parameters
- Request headers
- Request body schema (with types and validation rules)

**Response Specification:**

- Success response (status code + body structure)
- Error responses (all possible error codes)
- Response headers

**Code Examples:**

- cURL command
- JavaScript/TypeScript (fetch/axios)
- Python (requests)
- Other languages as needed

### Step 3: Add Usage Guidelines

I'll include:

- Getting started guide
- Authentication setup
- Common use cases
- Best practices
- Rate limiting details
- Pagination patterns
- Filtering and sorting options

### Step 4: Document Error Handling

Clear error documentation including:

- All possible error codes
- Error message formats
- Troubleshooting guide
- Common error scenarios and solutions

### Step 5: Create Interactive Examples

Where possible, I'll provide:

- Postman collection
- OpenAPI/Swagger specification
- Interactive code examples
- Sample responses

## Examples

### Example 1: REST API Endpoint Documentation

```markdown
## Create User

Creates a new user account.

**Endpoint:** `POST /api/v1/users`

**Authentication:** Required (Bearer token)

**Request Body:** \`\`\`json { "email": "user@example.com", // Required: Valid
email address "password": "SecurePass123!", // Required: Min 8 chars, 1
uppercase, 1 number "name": "John Doe", // Required: 2-50 characters "role":
"user" // Optional: "user" or "admin" (default: "user") } \`\`\`

**Success Response (201 Created):** \`\`\`json { "id": "usr_1234567890",
"email": "user@example.com", "name": "John Doe", "role": "user", "createdAt":
"2026-01-20T10:30:00Z", "emailVerified": false } \`\`\`

**Error Responses:**

- `400 Bad Request` - Invalid input data \`\`\`json { "error":
  "VALIDATION_ERROR", "message": "Invalid email format", "field": "email" }
  \`\`\`

- `409 Conflict` - Email already exists \`\`\`json { "error": "EMAIL_EXISTS",
  "message": "An account with this email already exists" } \`\`\`

- `401 Unauthorized` - Missing or invalid authentication token

**Example Request (cURL):** \`\`\`bash curl -X POST
https://api.example.com/api/v1/users \
 -H "Authorization: Bearer YOUR_TOKEN" \
 -H "Content-Type: application/json" \
 -d '{ "email": "user@example.com", "password": "SecurePass123!", "name": "John
Doe" }' \`\`\`

**Example Request (JavaScript):** \`\`\`javascript const response = await
fetch('https://api.example.com/api/v1/users', { method: 'POST', headers: {
'Authorization': `Bearer ${token}`, 'Content-Type': 'application/json' }, body:
JSON.stringify({ email: 'user@example.com', password: 'SecurePass123!', name:
'John Doe' }) });

const user = await response.json(); console.log(user); \`\`\`

**Example Request (Python):** \`\`\`python import requests

response = requests.post( 'https://api.example.com/api/v1/users', headers={
'Authorization': f'Bearer {token}', 'Content-Type': 'application/json' }, json={
'email': 'user@example.com', 'password': 'SecurePass123!', 'name': 'John Doe' }
)

user = response.json() print(user) \`\`\`
```

### Example 2: GraphQL API Documentation

```markdown
## User Query

Fetch user information by ID.

**Query:** \`\`\`graphql query GetUser($id: ID!) { user(id: $id) { id email name
role createdAt posts { id title publishedAt } } } \`\`\`

**Variables:** \`\`\`json { "id": "usr_1234567890" } \`\`\`

**Response:** \`\`\`json { "data": { "user": { "id": "usr_1234567890", "email":
"user@example.com", "name": "John Doe", "role": "user", "createdAt":
"2026-01-20T10:30:00Z", "posts": [ { "id": "post_123", "title": "My First Post",
"publishedAt": "2026-01-21T14:00:00Z" } ] } } } \`\`\`

**Errors:** \`\`\`json { "errors": [ { "message": "User not found",
"extensions": { "code": "USER_NOT_FOUND", "userId": "usr_1234567890" } } ] }
\`\`\`
```

### Example 3: Authentication Documentation

```markdown
## Authentication

All API requests require authentication using Bearer tokens.

### Getting a Token

**Endpoint:** `POST /api/v1/auth/login`

**Request:** \`\`\`json { "email": "user@example.com", "password":
"your-password" } \`\`\`

**Response:** \`\`\`json { "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
"expiresIn": 3600, "refreshToken": "refresh_token_here" } \`\`\`

### Using the Token

Include the token in the Authorization header:

\`\`\` Authorization: Bearer YOUR_TOKEN \`\`\`

### Token Expiration

Tokens expire after 1 hour. Use the refresh token to get a new access token:

**Endpoint:** `POST /api/v1/auth/refresh`

**Request:** \`\`\`json { "refreshToken": "refresh_token_here" } \`\`\`
```

## Best Practices

### ✅ Do This

- **Be Consistent** - Use the same format for all endpoints
- **Include Examples** - Provide working code examples in multiple languages
- **Document Errors** - List all possible error codes and their meanings
- **Show Real Data** - Use realistic example data, not "foo" and "bar"
- **Explain Parameters** - Describe what each parameter does and its constraints
- **Version Your API** - Include version numbers in URLs (/api/v1/)
- **Add Timestamps** - Show when documentation was last updated
- **Link Related Endpoints** - Help users discover related functionality
- **Include Rate Limits** - Document any rate limiting policies
- **Provide Postman Collection** - Make it easy to test your API

### ❌ Don't Do This

- **Don't Skip Error Cases** - Users need to know what can go wrong
- **Don't Use Vague Descriptions** - "Gets data" is not helpful
- **Don't Forget Authentication** - Always document auth requirements
- **Don't Ignore Edge Cases** - Document pagination, filtering, sorting
- **Don't Leave Examples Broken** - Test all code examples
- **Don't Use Outdated Info** - Keep documentation in sync with code
- **Don't Overcomplicate** - Keep it simple and scannable
- **Don't Forget Response Headers** - Document important headers

## Documentation Structure

### Recommended Sections

1. **Introduction**
   - What the API does
   - Base URL
   - API version
   - Support contact

2. **Authentication**
   - How to authenticate
   - Token management
   - Security best practices

3. **Quick Start**
   - Simple example to get started
   - Common use case walkthrough

4. **Endpoints**
   - Organized by resource
   - Full details for each endpoint

5. **Data Models**
   - Schema definitions
   - Field descriptions
   - Validation rules

6. **Error Handling**
   - Error code reference
   - Error response format
   - Troubleshooting guide

7. **Rate Limiting**
   - Limits and quotas
   - Headers to check
   - Handling rate limit errors

8. **Changelog**
   - API version history
   - Breaking changes
   - Deprecation notices

9. **SDKs and Tools**
   - Official client libraries
   - Postman collection
   - OpenAPI specification

## Common Pitfalls

### Problem: Documentation Gets Out of Sync

**Symptoms:** Examples don't work, parameters are wrong, endpoints return
different data **Solution:**

- Generate docs from code comments/annotations
- Use tools like Swagger/OpenAPI
- Add API tests that validate documentation
- Review docs with every API change

### Problem: Missing Error Documentation

**Symptoms:** Users don't know how to handle errors, support tickets increase
**Solution:**

- Document every possible error code
- Provide clear error messages
- Include troubleshooting steps
- Show example error responses

### Problem: Examples Don't Work

**Symptoms:** Users can't get started, frustration increases **Solution:**

- Test every code example
- Use real, working endpoints
- Include complete examples (not fragments)
- Provide a sandbox environment

### Problem: Unclear Parameter Requirements

**Symptoms:** Users send invalid requests, validation errors **Solution:**

- Mark required vs optional clearly
- Document data types and formats
- Show validation rules
- Provide example values

## Tools and Formats

### OpenAPI/Swagger

Generate interactive documentation:

```yaml
openapi: 3.0.0
info:
  title: My API
  version: 1.0.0
paths:
  /users:
    post:
      summary: Create a new user
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateUserRequest'
```

### Postman Collection

Export collection for easy testing:

```json
{
  "info": {
    "name": "My API",
    "schema": "https://schema.getpostman.com/json/collection/v2.1.0/collection.json"
  },
  "item": [
    {
      "name": "Create User",
      "request": {
        "method": "POST",
        "url": "{{baseUrl}}/api/v1/users"
      }
    }
  ]
}
```

## Related Skills

- `@doc-coauthoring` - For collaborative documentation writing
- `@copywriting` - For clear, user-friendly descriptions
- `@test-driven-development` - For ensuring API behavior matches docs
- `@systematic-debugging` - For troubleshooting API issues

## Additional Resources

- [OpenAPI Specification](https://swagger.io/specification/)
- [REST API Best Practices](https://restfulapi.net/)
- [GraphQL Documentation](https://graphql.org/learn/)
- [API Design Patterns](https://www.apiguide.com/)
- [Postman Documentation](https://learning.postman.com/docs/)

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**Pro Tip:** Keep your API documentation as close to your code as possible. Use
tools that generate docs from code comments to ensure they stay in sync!