Code Documenter Guide: Usage, Examples, and Best Practices for Beginners

Feb 14, 2026

Purpose

This post demonstrates how to use Code Documenter skill in Claude Code to automatically generate comprehensive documentation for your codebase.

Environment

Claude Code (latest)
claude-skills plugin installed
Git repository with code to document

What is Code Documenter?

Code Documenter is a skill in Claude Code that automatically generates documentation for your code. It analyzes your codebase and creates detailed documentation including:

Function and class descriptions
Parameter explanations
Return value documentation
Usage examples
Architecture overview

The skill helps you maintain up-to-date documentation without manual effort.

When should you use Code Documenter?

Starting a new project and need initial documentation
Adding new features to existing code
Onboarding team members to a codebase
Preparing code for open source release
Reviewing code clarity and completeness

Installation

First, install the claude-skills plugin:

npm install -g @jeffallan/claude-skills

Then activate the Code Documenter skill in your Claude Code configuration:

claude-skill install code-documenter

Verify installation:

claude-skill list

You should see code-documenter in the output.

Core Usage Patterns

Basic Invocation

The simplest way to use Code Documenter:

"Use code-documenter to document this file"

Or:

"Document this codebase using code-documenter"

Common Trigger Phrases

These phrases activate the skill:

“Document this code”
“Generate documentation for this function”
“Create API docs for this module”
“Explain this codebase”
“Write documentation for src/utils.js”

Typical Use Cases

1. Document a Single File

"Document /Users/zhaocaiwen/Project/src/utils.js"

2. Document an Entire Module

"Document the auth module"

3. Document with Specific Focus

"Document the error handling in this code"

Practical Examples

Example 1: Documenting a Utility Function

I have this utility function:

export function formatDate(date, options = {}) {
  const {
    locale = 'en-US',
    includeTime = false
  } = options

  const formatter = new Intl.DateTimeFormat(locale, {
    year: 'numeric',
    month: 'long',
    day: 'numeric',
    ...(includeTime && {
      hour: '2-digit',
      minute: '2-digit'
    })
  })

  return formatter.format(new Date(date))
}

I run:

"Use code-documenter to document this file"

Code Documenter generates:

/**
 * Formats a date into a human-readable string using Intl.DateTimeFormat
 *
 * @param {Date|string|number} date - The date to format. Can be a Date object, ISO string, or timestamp
 * @param {Object} options - Configuration options for formatting
 * @param {string} options.locale - The locale to use for formatting (default: 'en-US')
 * @param {boolean} options.includeTime - Whether to include time in the output (default: false)
 * @returns {string} The formatted date string
 *
 * @example
 * // Format date in English
 * formatDate('2024-01-15')
 * // Returns: 'January 15, 2024'
 *
 * @example
 * // Format date with time in French
 * formatDate('2024-01-15', { locale: 'fr-FR', includeTime: true })
 * // Returns: '15 janvier 2024 à 00:00'
 */
export function formatDate(date, options = {}) {
  const {
    locale = 'en-US',
    includeTime = false
  } = options

  const formatter = new Intl.DateTimeFormat(locale, {
    year: 'numeric',
    month: 'long',
    day: 'numeric',
    ...(includeTime && {
      hour: '2-digit',
      minute: '2-digit'
    })
  })

  return formatter.format(new Date(date))
}

You can see that the documentation includes:

Clear description of what the function does
Parameter types and purposes
Return value explanation
Usage examples
Default values explained

Example 2: Documenting a Class

I have this class:

export class UserManager {
  private users: Map<string, User>

  constructor() {
    this.users = new Map()
  }

  addUser(id: string, user: User): void {
    this.users.set(id, user)
  }

  getUser(id: string): User | undefined {
    return this.users.get(id)
  }

  deleteUser(id: string): boolean {
    return this.users.delete(id)
  }

  listUsers(): User[] {
    return Array.from(this.users.values())
  }
}

I ask Code Documenter to explain the architecture:

"Use code-documenter to document this class and explain its design"

The skill generates comprehensive documentation including:

/**
 * Manages user storage and retrieval using an in-memory Map structure.
 *
 * This class provides CRUD operations for user management. It uses a Map
 * for O(1) lookup performance and maintains user data in memory.
 *
 * @example
 * const manager = new UserManager()
 * manager.addUser('user1', { name: 'Alice', email: '[email protected]' })
 * const user = manager.getUser('user1')
 *
 * @architecture
 * - Storage: Map<string, User> for fast key-based access
 * - Operations: O(1) for get, add, delete
 * - Memory: All users stored in memory
 * - Thread-safety: Not thread-safe (single-threaded JavaScript)
 */
export class UserManager {
  /**
   * Internal storage mapping user IDs to User objects
   */
  private users: Map<string, User>

  /**
   * Creates a new UserManager with empty user storage
   */
  constructor() {
    this.users = new Map()
  }

  /**
   * Adds or updates a user in the storage
   *
   * @param id - Unique identifier for the user
   * @param user - User object to store
   *
   * @example
   * manager.addUser('user1', { name: 'Alice', email: '[email protected]' })
   */
  addUser(id: string, user: User): void {
    this.users.set(id, user)
  }

  /**
   * Retrieves a user by ID
   *
   * @param id - User ID to look up
   * @returns The User object if found, undefined otherwise
   *
   * @example
   * const user = manager.getUser('user1')
   * if (user) {
   *   console.log(user.name)
   * }
   */
  getUser(id: string): User | undefined {
    return this.users.get(id)
  }

  /**
   * Removes a user from storage
   *
   * @param id - User ID to delete
   * @returns true if user was deleted, false if ID not found
   *
   * @example
   * const wasDeleted = manager.deleteUser('user1')
   * console.log(wasDeleted ? 'Deleted' : 'Not found')
   */
  deleteUser(id: string): boolean {
    return this.users.delete(id)
  }

  /**
   * Gets all users as an array
   *
   * @returns Array of all User objects in storage
   *
   * @example
   * const allUsers = manager.listUsers()
   * allUsers.forEach(user => console.log(user.name))
   */
  listUsers(): User[] {
    return Array.from(this.users.values())
  }
}

Example 3: Documenting API Routes

I have these Express routes:

import express from 'express'
const router = express.Router()

router.get('/users', async (req, res) => {
  const { page = 1, limit = 10 } = req.query
  const users = await User.find()
    .skip((page - 1) * limit)
    .limit(limit)
  res.json(users)
})

router.post('/users', async (req, res) => {
  const user = await User.create(req.body)
  res.status(201).json(user)
})

router.get('/users/:id', async (req, res) => {
  const user = await User.findById(req.params.id)
  if (!user) {
    return res.status(404).json({ error: 'User not found' })
  }
  res.json(user)
})

I run:

"Document these API routes with code-documenter"

Code Documenter generates API documentation:

/**
 * User management API routes
 *
 * Provides CRUD endpoints for user operations including:
 * - List users with pagination
 * - Create new user
 * - Get user by ID
 *
 * @basepath /api
 */

/**
 * @route GET /users
 * @description Retrieves a paginated list of users
 * @queryparam {number} page - Page number (default: 1)
 * @queryparam {number} limit - Items per page (default: 10)
 * @response {200} Array of user objects
 * @response {500} Server error
 *
 * @example
 * GET /users?page=2&limit=20
 * Response:
 * [
 *   { "_id": "123", "name": "Alice" },
 *   { "_id": "456", "name": "Bob" }
 * ]
 */
router.get('/users', async (req, res) => {
  const { page = 1, limit = 10 } = req.query
  const users = await User.find()
    .skip((page - 1) * limit)
    .limit(limit)
  res.json(users)
})

/**
 * @route POST /users
 * @description Creates a new user
 * @bodyparam {Object} user - User data
 * @bodyparam {string} user.name - User's full name
 * @bodyparam {string} user.email - User's email address
 * @response {201} Created user object
 * @response {400} Validation error
 *
 * @example
 * POST /users
 * Body: { "name": "Charlie", "email": "[email protected]" }
 * Response: { "_id": "789", "name": "Charlie", "email": "[email protected]" }
 */
router.post('/users', async (req, res) => {
  const user = await User.create(req.body)
  res.status(201).json(user)
})

/**
 * @route GET /users/:id
 * @description Retrieves a single user by ID
 * @urlparam {string} id - User's unique identifier
 * @response {200} User object
 * @response {404} User not found error
 *
 * @example
 * GET /users/123
 * Response: { "_id": "123", "name": "Alice" }
 *
 * @example
 * GET /users/999
 * Response: { "error": "User not found" }
 */
router.get('/users/:id', async (req, res) => {
  const user = await User.findById(req.params.id)
  if (!user) {
    return res.status(404).json({ error: 'User not found' })
  }
  res.json(user)
})

Best Practices

DO

1. Document at the right time

Document code when it’s stable, not during rapid prototyping
Update documentation when you change APIs
Run Code Documenter after refactoring

2. Combine with manual review

Review generated documentation for accuracy
Add business context that AI can’t know
Fix any unclear or misleading descriptions

3. Use consistent style

Stick to JSDoc, TSDoc, or your team’s standard
Include examples for complex functions
Document edge cases and error conditions

4. Document the why, not just the what

// GOOD: Explains reasoning
/**
 * Uses Map instead of object for O(1) lookups and symbol keys
 * This allows us to use non-string keys and prevents prototype pollution
 */

// AVOID: Just restates code
/**
 * Creates a new Map to store data
 */

5. Keep examples minimal but clear

// GOOD: Simple, focused example
formatDate('2024-01-15') // Returns: 'January 15, 2024'

// AVOID: Complex, distracting example
formatDate(getUserInputDate().toISOString(), {
  locale: getNavigatorLanguage(),
  includeTime: shouldIncludeTimeBasedOnUserRole()
})

DON’T

1. Don’t document obvious code

// AVOID: Waste of time
/**
 * Sets the x variable to 5
 */
const x = 5

// BETTER: No documentation needed
const x = 5

2. Don’t let documentation get stale

Don’t change code without updating docs
Don’t ignore warnings about outdated documentation
Don’t leave TODO comments in docs forever

3. Don’t use vague descriptions

// AVOID: Unclear purpose
/**
 * Processes the data
 */

// BETTER: Specific and clear
/**
 * Validates user input and sanitizes HTML to prevent XSS attacks
 */

4. Don’t duplicate implementation details

// AVOID: Restating the code
/**
 * Returns true if the array length equals zero
 */
function isEmpty(arr) {
  return arr.length === 0
}

// BETTER: Explain the intent
/**
 * Checks if a collection has no elements
 */
function isEmpty(arr) {
  return arr.length === 0
}

5. Don’t skip error documentation

// AVOID: No error info
/**
 * Gets user data
 */
async function getUser(id) { ... }

// BETTER: Includes error cases
/**
 * Gets user data by ID
 * @throws {NotFoundError} If user doesn't exist
 * @throws {DatabaseError} If database connection fails
 */
async function getUser(id) { ... }

Complementary Skills

code-reviewer: Checks code quality before documentation
security-review: Identifies security issues to document
tdd-guide: Ensures tests cover documented behavior

Documentation Standards

JSDoc: Standard for JavaScript documentation
TSDoc: TypeScript documentation format
OpenAPI: REST API documentation specification

Learning Resources

Summary

In this post, I showed how to use Code Documenter skill in Claude Code to automatically generate comprehensive documentation for your code. The key point is that Code Documenter saves time and improves consistency, but you should still review and enhance the generated documentation with business context and edge cases that only you know.

Final Words + More Resources

My intention with this article was to help others share my knowledge and experience. If you want to contact me, you can contact by email: Email me

Here are also the most important links from this article along with some further resources that will help you in this scope:

👨‍💻 claude-skills Documentation
👨‍💻 claude-skills GitHub Repository

Oh, and if you found these resources useful, don’t forget to support me by starring the repo on GitHub!