Code Documenter

Overview

Add or update professional documentation to code files following language-specific best practices and industry conventions. Reduce cognitive load by providing clear, well-structured documentation that explains "why" rather than just "what."

Supported Languages

• Python: PEP 257 docstrings with type hints (Google/NumPy style)
• JavaScript/TypeScript: JSDoc/TSDoc comments with examples
• C/C++: Doxygen-style documentation with memory safety notes
• Dart/Flutter: Triple-slash comments with widget documentation

When to Use This Skill

This skill should be used when:

1. Explicit request: User asks to "document this code" or "add documentation"
2. Auto-detection scenarios:
   • New code has been written without documentation
   • Existing code lacks adequate docstrings/comments
   • Public APIs are undocumented
   • Complex logic needs explanation
3. After code changes: When implementing features or fixing bugs
4. Before commits: When preparing code for review

Documentation Workflow

Step 1: Identify Files to Document

Determine which files need documentation:

• If user provides file path(s), use those specific files
• If user says "document my changes," check git status for modified files
• If user says "document this," use the file currently in context
• For "document everything," ask user to confirm scope

Step 2: Detect Language and Load Standards

For each file, detect the programming language by extension:

• .py → Python: Read references/python_docs.md
• .js, .ts, .jsx, .tsx → JavaScript/TypeScript: Read references/javascript_typescript_docs.md
• .cpp, .cc, .h, .hpp, .c → C/C++: Read references/cpp_docs.md
• .dart → Dart/Flutter: Read references/dart_flutter_docs.md

If language is unsupported, inform user and skip the file.

Load only the relevant reference file into context to avoid token waste. Do not load all language references at once.

Step 3: Analyze Code Structure

Read the target file and identify:

1. Top-level documentation: Module/file docstring
2. Classes/Interfaces: Class documentation, attributes, purpose
3. Functions/Methods: Parameter descriptions, return values, exceptions
4. Complex logic: Areas needing inline comments
5. Constants/Enums: Purpose and usage documentation

Step 4: Apply Documentation Standards

Following the loaded language standards, add documentation at the standard detail level:

• Document all public APIs (classes, functions, methods)
• Add module/file-level documentation
• Include parameter and return value descriptions
• Add inline comments for non-obvious logic
• Skip private methods unless they're complex
• Include usage examples for complex APIs

Key Principles:

• First line should be a concise one-line summary
• Explain "why" in comments, not "what"
• Use proper formatting for the language (PEP 257, JSDoc, Doxygen, etc.)
• Include type information where applicable
• Add examples for complex usage patterns
• Note side effects, thread safety, memory ownership

Step 5: Preserve Code Logic

CRITICAL: Do not modify the actual code logic, only add documentation.

• Add docstrings/comments without changing functionality
• Preserve existing formatting and style
• Keep all existing code intact
• Only add documentation blocks and inline comments

Step 6: Apply Changes

Use the Edit tool to add documentation:

1. For module/file documentation: Add at the very top of the file
2. For class documentation: Add immediately before class definition
3. For function documentation: Add immediately before function definition
4. For inline comments: Add on line above or at end of complex statements

Make multiple small, focused edits rather than one large replacement.

Step 7: Verify and Report

After documenting:

1. Confirm all public APIs are documented
2. Check that complex logic has explanatory comments
3. Verify formatting matches language conventions
4. Report summary to user:
   • Files documented
   • Documentation elements added (modules, classes, functions)
   • Any issues or skipped items

Language-Specific Quick Reference

Python

"""Module-level docstring explaining purpose."""

class Example:
    """Class docstring with purpose.

    Attributes:
        attr_name: Description with type info
    """

    def method(self, param: str) -> bool:
        """One-line description.

        Args:
            param: Parameter description

        Returns:
            Return value description

        Raises:
            ExceptionType: When this occurs
        """

JavaScript/TypeScript

/**
 * Function description.
 *
 * @param param - Parameter description
 * @returns Return value description
 * @throws {ErrorType} When error occurs
 *
 * @example
 * ```typescript
 * const result = example('value');
 * ```
 */
function example(param: string): boolean {

C/C++

/**
 * @file filename.h
 * @brief Brief file description
 */

/**
 * @brief Function description
 *
 * @param param Parameter description
 * @return Return value description
 *
 * @warning Important warnings
 * @threadsafe Thread safety information
 */
bool example(const std::string& param);

Dart/Flutter

/// Function description.
///
/// Detailed explanation if needed.
///
/// Returns description.
///
/// Throws [ExceptionType] when error occurs.
///
/// Example:
/// ```dart
/// final result = example('value');
/// ```
bool example(String param) {

Examples

Example 1: Document Single Python File

User request: "Document this file"

Process:

1. Detect file is Python (.py extension)
2. Read references/python_docs.md
3. Analyze file structure (modules, classes, functions)
4. Add PEP 257 docstrings following Google style
5. Add inline comments for complex logic
6. Report: "Added module docstring, 3 class docstrings, 12 function docstrings, and 8 inline comments"

Example 2: Document Changed TypeScript Files

User request: "Document my changes"

Process:

1. Check git status for modified .ts/.tsx files
2. For each file: detect TypeScript
3. Read references/javascript_typescript_docs.md
4. Add JSDoc comments to new/modified functions
5. Update existing docstrings if signatures changed
6. Report: "Documented 5 TypeScript files with 23 functions"

Example 3: Document C++ Header

User request: "Add documentation to timer.h"

Process:

1. Detect C++ from .h extension
2. Read references/cpp_docs.md
3. Add file-level @file and @brief
4. Document all public classes and methods
5. Add @note for thread safety, memory ownership
6. Report: "Added file header, 2 class docs, 15 method docs with threading notes"

Advanced Features

Batch Documentation

When documenting multiple files:

1. Group files by language to minimize reference file loading
2. Process all Python files, then JavaScript, then C++, etc.
3. Load each language reference only once
4. Report progress: "Documenting file 3 of 8..."
5. Provide summary at end with breakdown by language

Smart Detection of Documentation Needs

Automatically identify what needs documentation:

• Missing module docstrings: Top of file has no documentation
• Undocumented public APIs: Classes/functions lack docstrings
• Complex logic: Code blocks with high cyclomatic complexity
• Recent changes: Functions modified in recent commits
• TODO/FIXME comments: Areas marked for attention

Handling Edge Cases

Mixed languages in project: Document each file in its native style

Partially documented code: Fill in gaps without duplicating existing docs

Generated code: Skip auto-generated files (ask user if uncertain)

Test files: Use simpler documentation (purpose and what is tested)

Legacy code: Add minimal documentation first, suggest comprehensive pass

Best Practices

1. Read the file first: Always read the target file before documenting
2. Load references as needed: Don't load all language references at once
3. Multiple small edits: Make focused edits rather than large replacements
4. Preserve formatting: Match existing code style and indentation
5. Explain "why" not "what": Focus comments on reasoning, not mechanics
6. Include examples: Add usage examples for complex APIs
7. Note constraints: Document preconditions, thread safety, ownership
8. Update existing docs: If code changed, update related documentation

Resources

references/

Language-specific documentation standards:

• python_docs.md - PEP 257 conventions, type hints, Google/NumPy style
• javascript_typescript_docs.md - JSDoc/TSDoc standards with examples
• cpp_docs.md - Doxygen conventions, thread safety, memory management
• dart_flutter_docs.md - Dart doc comments, Flutter widget documentation

Load only the relevant reference when documenting files in that language.