SKILL.md
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When to Use This Skill
Always load this skill when:
- User asks to "document", "create docs", or "write documentation" for any code
- User requests a README, API reference, or developer guide
- User shares a codebase or repository and wants documentation generated
- User asks to improve or update existing documentation
- User needs architecture documentation, including diagrams
- User requests a changelog or migration guide
Documentation Workflow
Phase 1: Codebase Analysis
Before writing any documentation, thoroughly understand the codebase.
#### Step 1.1: Project Discovery
Identify the project fundamentals:
Field
How to Determine
Language(s)
Check file extensions, package.json, pyproject.toml, go.mod, Cargo.toml, etc.
Framework
Look at dependencies for known frameworks (React, Django, Express, Spring, etc.)
Build System
Check for Makefile, CMakeLists.txt, webpack.config.js, build.gradle, etc.
Package Manager
npm/yarn/pnpm, pip/uv/poetry, cargo, go modules, etc.
Project Structure
Map out the directory tree to understand the architecture
Entry Points
Find main files, CLI entry points, exported modules
Existing Docs
Check for existing README, docs/, wiki, or inline documentation
#### Step 1.2: Code Structure Analysis
Use sandbox tools to explore the codebase:
# Get directory structure
ls /mnt/user-data/uploads/project-dir/
# Read key files
read_file /mnt/user-data/uploads/project-dir/package.json
read_file /mnt/user-data/uploads/project-dir/pyproject.toml
# Search for public API surfaces
grep -r "export " /mnt/user-data/uploads/project-dir/src/
grep -r "def " /mnt/user-data/uploads/project-dir/src/ --include="*.py"
grep -r "func " /mnt/user-data/uploads/project-dir/ --include="*.go"#### Step 1.3: Identify Documentation Scope
Based on analysis, determine what documentation to produce:
Project Size
Recommended Documentation
Single file / script
Inline comments + usage header
Small library
README with API reference
Medium project
README + API docs + examples
Large project
README + Architecture + API + Contributing + Changelog
Phase 2: Documentation Generation
#### Step 2.1: README Generation
Every project needs a README. Follow this structure:
# Project Name
[One-line project description — what it does and why it matters]
[](#) [](#)
## Features
- [Key feature 1 — brief description]
- [Key feature 2 — brief description]
- [Key feature 3 — brief description]
## Quick Start
### Prerequisites
- [Prerequisite 1 with version requirement]
- [Prerequisite 2 with version requirement]
### Installation
[Installation commands with copy-paste-ready code blocks]
### Basic Usage
[Minimal working example that demonstrates core functionality]
## Documentation
- [Link to full API reference if separate]
- [Link to architecture docs if separate]
- [Link to examples directory if applicable]
## API Reference
[Inline API reference for smaller projects OR link to generated docs]
## Configuration
[Environment variables, config files, or runtime options]
## Examples
[2-3 practical examples covering common use cases]
## Development
### Setup
[How to set up a development environment]
### Testing
[How to run tests]
### Building
[How to build the project]
## Contributing
[Contribution guidelines or link to CONTRIBUTING.md]
## License
[License information]#### Step 2.2: API Reference Generation
For each public API surface, document:
Function / Method Documentation:
### `functionName(param1, param2, options?)`
Brief description of what this function does.
**Parameters:**
| Parameter | Type | Required | Default | Description |
|-----------|------|----------|---------|-------------|
| `param1` | `string` | Yes | — | Description of param1 |
| `param2` | `number` | Yes | — | Description of param2 |
| `options` | `Object` | No | `{}` | Configuration options |
| `options.timeout` | `number` | No | `5000` | Timeout in milliseconds |
**Returns:** `Promise<Result>` — Description of return value
**Throws:**
- `ValidationError` — When param1 is empty
- `TimeoutError` — When the operation exceeds the timeout
**Example:**
\`\`\`javascript
const result = await functionName("hello", 42, { timeout: 10000 });
console.log(result.data);
\`\`\`Class Documentation:
### `ClassName`
Brief description of the class and its purpose.
**Constructor:**
\`\`\`javascript
new ClassName(config)
\`\`\`
| Parameter | Type | Description |
|-----------|------|-------------|
| `config.option1` | `string` | Description |
| `config.option2` | `boolean` | Description |
**Methods:**
- [`method1()`](#method1) — Brief description
- [`method2(param)`](#method2) — Brief description
**Properties:**
| Property | Type | Description |
|----------|------|-------------|
| `property1` | `string` | Description |
| `property2` | `number` | Read-only. Description |#### Step 2.3: Architecture Documentation
For medium-to-large projects, include architecture documentation:
# Architecture Overview
## System Diagram
[Include a Mermaid diagram showing the high-level architecture]
\`\`\`mermaid
graph TD
A[Client] --> B[API Gateway]
B --> C[Service A]
B --> D[Service B]
C --> E[(Database)]
D --> E
\`\`\`
## Component Overview
### Component Name
- **Purpose**: What this component does
- **Location**: `src/components/name/`
- **Dependencies**: What it depends on
- **Public API**: Key exports or interfaces
## Data Flow
[Describe how data flows through the system for key operations]
## Design Decisions
### Decision Title
- **Context**: What situation led to this decision
- **Decision**: What was decided
- **Rationale**: Why this approach was chosen
- **Trade-offs**: What was sacrificed#### Step 2.4: Inline Code Documentation
Generate language-appropriate inline documentation:
Python (Docstrings — Google style):
def process_data(input_path: str, options: dict | None = None) -> ProcessResult:
"""Process data from the given file path.
Reads the input file, applies transformations based on the provided
options, and returns a structured result object.
Args:
input_path: Absolute path to the input data file.
Supports CSV, JSON, and Parquet formats.
options: Optional configuration dictionary.
- "validate" (bool): Enable input validation. Defaults to True.
- "format" (str): Output format ("json" or "csv"). Defaults to "json".
Returns:
A ProcessResult containing the transformed data and metadata.
Raises:
FileNotFoundError: If input_path does not exist.
ValidationError: If validation is enabled and data is malformed.
Example:
>>> result = process_data("/data/input.csv", {"validate": True})
>>> print(result.row_count)
1500
"""TypeScript (JSDoc / TSDoc):
/**
* Fetches user data from the API and transforms it for display.
*
* @param userId - The unique identifier of the user
* @param options - Configuration options for the fetch operation
* @param options.includeProfile - Whether to include the full profile. Defaults to `false`.
* @param options.cache - Cache duration in seconds. Set to `0` to disable.
* @returns The transformed user data ready for rendering
* @throws {NotFoundError} When the user ID does not exist
* @throws {NetworkError} When the API is unreachable
*
* @example
* ```ts
* const user = await fetchUser("usr_123", { includeProfile: true });
* console.log(user.displayName);
* ```
*/Go (GoDoc):
// ProcessData reads the input file at the given path, applies the specified
// transformations, and returns the processed result.
//
// The input path must be an absolute path to a CSV or JSON file.
// If options is nil, default options are used.
//
// ProcessData returns an error if the file does not exist or cannot be parsed.
func ProcessData(inputPath string, options *ProcessOptions) (*Result, error) {Phase 3: Quality Assurance
#### Step 3.1: Documentation Completeness Check
Verify the documentation covers:
- What it is — Clear project description that a newcomer can understand
- Why it exists — Problem it solves and value proposition
- How to install — Copy-paste-ready installation commands
- How to use — At least one minimal working example
- API surface — All public functions, classes, and types documented
- Configuration — All environment variables, config files, and options
- Error handling — Common errors and how to resolve them
- Contributing — How to set up dev environment and submit changes
#### Step 3.2: Quality Standards
Standard
Check
Accuracy
Every code example must actually work with the described API
Completeness
No public API surface left undocumented
Consistency
Same formatting and structure throughout
Freshness
Documentation matches the current code, not an older version
Accessibility
No jargon without explanation, acronyms defined on first use
Examples
Every complex concept has at least one practical example
#### Step 3.3: Cross-reference Validation
Ensure:
- All mentioned file paths exist in the project
- All referenced functions and classes exist in the code
- All code examples use the correct function signatures
- Version numbers match the project's actual version
- All links (internal and external) are valid
Documentation Style Guide
Writing Principles
- Lead with the "why" — Before explaining how something works, explain why it exists
- Progressive disclosure — Start simple, add complexity gradually
- Show, don't tell — Prefer code examples over lengthy explanations
- Active voice — "The function returns X" not "X is returned by the function"
- Present tense — "The server starts on port 8080" not "The server will start on port 8080"
- Second person — "You can configure..." not "Users can configure..."
Formatting Rules
- Use ATX-style headers (
#,##,###)
- Use fenced code blocks with language specification (
python,bash)
- Use tables for structured information (parameters, options, configuration)
- Use admonitions for important notes, warnings, and tips
- Keep line length readable (wrap prose at ~80-100 characters in source)
- Use
code formattingfor function names, file paths, variable names, and CLI commands
Language-Specific Conventions
Language
Doc Format
Style Guide
Python
Google-style docstrings
PEP 257
TypeScript/JavaScript
TSDoc / JSDoc
TypeDoc conventions
Go
GoDoc comments
Effective Go
Rust
Rustdoc (///)
Rust API Guidelines
Java
Javadoc
Oracle Javadoc Guide
C/C++
Doxygen
Doxygen manual
Output Handling
After generation:
- Save documentation files to
/mnt/user-data/outputs/
- For multi-file documentation, maintain the project directory structure
- Present generated files to the user using the
present_filestool
- Offer to iterate on specific sections or adjust the level of detail
- Suggest additional documentation that might be valuable
Notes
- Always analyze the actual code before writing documentation — never guess at API signatures or behavior
- When existing documentation exists, preserve its structure unless the user explicitly asks for a rewrite
- For large codebases, prioritize documenting the public API surface and key abstractions first
- Documentation should be written in the same language as the project's existing docs; default to English if none exist
- When generating changelogs, use the Keep a Changelog format
- This skill works well in combination with the
deep-researchskill for documenting third-party integrations or dependencies