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Why Documentation is the Fastest Way to Improve Code Quality

Published on June 6, 2025 | 7 min read

Here's a counterintuitive truth: the fastest way to improve your code isn't refactoring, adding tests, or code reviews. It's writing documentation.

I know what you're thinking. Documentation feels like busy work—something you do after the code is done, not something that actually makes the code better. But here's what I've learned after helping hundreds of developers generate documentation for their codebases: the act of documenting code forces you to confront its flaws.

When you try to explain what your code does, you quickly discover what's wrong with it. And once you see those problems clearly, fixing them becomes obvious.

The Documentation Mirror Effect

Think about the last time you tried to explain a complex piece of code to someone else. Remember that moment when you started a sentence like "So this function takes a parameter that..." and then stopped, realizing you couldn't actually explain what the parameter was for?

That's the documentation mirror effect. Documentation holds up a mirror to your code and shows you exactly how complex, confusing, or poorly designed it really is.

Here's a real example. A developer was trying to document this function:

function processUserData(data: any, options?: any): any {
  if (options?.includeMetadata) {
    // ... 50 lines of complex logic
  }
  // ... more conditional logic
  return result;
}

When they sat down to write the documentation, they realized they couldn't answer basic questions:

  • What shape should data have?
  • What options are available?
  • What does the return value look like?
  • When would you use this function?

Trying to document this function revealed that it was doing too many things and had an unclear interface. The documentation attempt led to this refactor:

interface UserProfile {
  id: string;
  name: string;
  email: string;
}

interface ProcessingOptions {
  includeMetadata: boolean;
  validateEmail: boolean;
}

interface ProcessedUser extends UserProfile {
  metadata?: UserMetadata;
  isValid: boolean;
}

/**
 * Processes and validates user profile data.
 * Optionally enriches with metadata for admin views.
 */
function processUserProfile(
  profile: UserProfile, 
  options: ProcessingOptions = {}
): ProcessedUser {
  // Clear, focused implementation
}

The difference is dramatic. The second version has clear types, focused responsibility, and obvious usage patterns. The documentation effort forced better design.

Five Ways Documentation Improves Code Quality

1. Documentation Reveals Naming Problems

Bad names hide in code but stick out in documentation. When you write "The handleStuff function processes various user inputs and updates the system state," you immediately see the problem.

Before documenting:

function handleStuff(thing: any, flag: boolean) {
  // implementation
}

After trying to document it:

function validateAndSaveUserProfile(profile: UserProfile, shouldNotify: boolean) {
  // much clearer implementation
}

The act of writing documentation forces you to use precise language, which reveals when your code isn't using precise names.

2. Documentation Exposes Over-Complex Abstractions

If you can't explain your abstraction simply, it's probably too complex. This is the rubber duck effect applied to API design.

I once saw a developer struggle to document a "flexible data processor" that could handle "any kind of transformation." After 30 minutes of trying to write clear documentation, they realized they'd built an over-engineered solution to a simple problem.

The documentation process led them to replace a complex generic system with three simple, focused functions that were easy to understand, test, and maintain.

3. Documentation Forces You to Think About Edge Cases

When you document a function's behavior, you have to consider what happens in unusual situations:

/**
 * Calculates the average of an array of numbers.
 * 
 * @param numbers - Array of numbers to average
 * @returns The arithmetic mean
 * 
 * @throws {Error} When array is empty
 * @throws {TypeError} When array contains non-numeric values
 */
function calculateAverage(numbers: number[]): number {
  if (numbers.length === 0) {
    throw new Error('Cannot calculate average of empty array');
  }
  
  const sum = numbers.reduce((acc, num) => {
    if (typeof num !== 'number' || isNaN(num)) {
      throw new TypeError('Array must contain only valid numbers');
    }
    return acc + num;
  }, 0);
  
  return sum / numbers.length;
}

Writing the documentation made the developer think: "What if the array is empty? What if it contains non-numbers?" This led to better error handling and more robust code.

4. Documentation Reveals Missing Abstractions

Sometimes documenting code shows you that you're repeating the same complex explanations over and over. That's a sign you need better abstractions.

If you find yourself writing the same paragraph to explain multiple functions, you probably need to extract that common behavior into a shared utility or class.

5. Documentation Highlights Inconsistent Interfaces

When you document multiple related functions, inconsistencies become obvious:

Before documentation review:

function createUser(userData: UserData): Promise<User>
function updateUser(id: string, changes: Partial<UserData>): Promise<void>
function getUser(userId: string): Promise<User | null>
function deleteUser(user_id: string): Promise<boolean>

After noticing inconsistencies in documentation:

function createUser(userData: UserData): Promise<User>
function updateUser(userId: string, changes: Partial<UserData>): Promise<User>
function getUser(userId: string): Promise<User | null>
function deleteUser(userId: string): Promise<void>

The documentation process revealed inconsistent parameter naming and return types, leading to a more cohesive API.

The Documentation-Driven Development Process

Here's how to use documentation as a code quality tool:

Step 1: Write Documentation First (Sometimes)

For complex functions or public APIs, try writing the documentation before the implementation:

/**
 * Authenticates a user and returns a JWT token.
 * 
 * @param email - User's email address
 * @param password - User's password
 * @returns Promise that resolves to authentication result
 * 
 * @example
 * ```typescript
 * const result = await authenticateUser('user@example.com', 'password123');
 * if (result.success) {
 *   console.log('Token:', result.token);
 * } else {
 *   console.error('Auth failed:', result.error);
 * }
 * ```
 */
async function authenticateUser(
  email: string, 
  password: string
): Promise<AuthResult> {
  // TODO: implement
}

This forces you to think through the interface before you get lost in implementation details.

Step 2: Use Documentation Generation to Find Problems

Tools like Syntax Scribe can automatically generate documentation from your code. When you review the generated docs, problems jump out:

  • Functions with too many parameters
  • Unclear return types
  • Missing error handling
  • Inconsistent naming patterns
  • Over-complex interfaces

The generated documentation acts like a code review focused specifically on clarity and usability.

Step 3: Apply the "Explain It to a Junior Developer" Test

If you can't explain your code clearly to someone with less experience, it's probably too complex. This test catches:

  • Over-abstracted code
  • Unclear variable names
  • Hidden dependencies
  • Implicit assumptions

Real-World Impact: The Cleanup Cascade

Here's what typically happens when teams start prioritizing documentation:

Week 1: Developers struggle to document existing code, realizing how unclear it is.

Week 2: Small refactors start happening as developers fix obvious naming and structure issues.

Week 3: Larger architectural problems become visible as teams try to document how systems work together.

Week 4: New code starts being written with documentation in mind, leading to clearer interfaces from the start.

One team I worked with saw their average pull request size decrease by 40% after implementing documentation-driven development. Why? Because clear, well-documented code requires fewer explanations and edge case fixes during review.

The Syntax Scribe Advantage

At Syntax Scribe, we've seen this pattern repeatedly: teams that generate documentation regularly write better code. Here's why our approach amplifies the effect:

Automated generation means you see documentation for all your code, not just the parts you remember to document manually. This reveals inconsistencies across your entire codebase.

Real-time feedback through generated docs shows you immediately how clear (or unclear) your interfaces are.

Team visibility ensures everyone sees the documentation, creating social pressure for better code design.

When documentation generation is frictionless, it becomes a regular part of development rather than an afterthought.

Making It Practical

Want to use documentation to improve your code quality? Start here:

Quick Wins (This Week)

  1. Pick your worst function and try to document it. What problems do you discover?
  2. Document your public API - even if it's just internal. Unclear interfaces will become obvious.
  3. Use generated documentation to review your code from a user's perspective.

Systematic Approach (This Month)

  1. Add documentation to your definition of done - no PR gets merged without clear documentation.
  2. Review generated docs in stand-ups - discuss unclear interfaces as a team.
  3. Document before implementing for new features - use it as a design tool.

Cultural Change (This Quarter)

  1. Make documentation visible - put it somewhere the team sees it regularly.
  2. Celebrate good documentation - recognize developers who write clear explanations.
  3. Use documentation in code reviews - ask "Is this interface clear from the docs?"

The Surprising Result

Teams that embrace documentation-driven development report an unexpected benefit: they enjoy their code more. Clear, well-documented code is satisfying to work with. It's easier to modify, debug, and extend.

And here's the kicker: clear code is fast code. Not because it runs faster, but because developers can understand and modify it faster. In a world where developer time is the primary constraint, that's the most important performance optimization you can make.

Conclusion

Documentation isn't just communication—it's a thinking tool. It forces you to articulate what your code does, which reveals what it should do and how it could do it better.

The fastest way to improve code quality isn't adding more tests or stricter linting rules. It's requiring that every piece of code be explainable to another human being. When code can't be explained clearly, it gets rewritten clearly.

Make documentation a first-class part of your development process, and watch your code quality improve almost immediately. Your future self—and your teammates—will thank you.

Ready to use documentation as a code quality tool? Try Syntax Scribe to automatically generate clear documentation from your TypeScript and JavaScript projects, and discover what your code is really saying.