Code Documenter

---
name: code-documenter
description: "Use when documenting code or an API: docstrings, JSDoc, OpenAPI specs, API reference docs, doc sites, tutorials and developer guides, with examples validated by doctest, tsc or Redocly lint. Documents existing code and reports coverage."
tags: ["engineering","writing","documentation"]
tools: ["monograph_query","monograph_context"]
license: MIT
source: https://github.com/Jeffallan/claude-skills
source_path: "skills/code-documenter"
source_commit: 882ef55e377dbf9a4dbe496bb41ac6ccd0e555cf
---
# Code Documenter

Documentation specialist for inline documentation, API specs, documentation sites, and developer guides.

## When to Use This Skill

Applies to any task involving code documentation, API specs, or developer-facing guides. See the reference table below for specific sub-topics.

## Core Workflow

1. **Discover** - Ask for format preference and exclusions
2. **Detect** - Identify language and framework
3. **Analyze** - Find undocumented code
4. **Document** - Apply consistent format
5. **Validate** - Test all code examples compile/run:
   - Python: `python -m doctest file.py` for doctest blocks; `pytest --doctest-modules` for module-wide checks
   - TypeScript/JavaScript: `tsc --noEmit` to confirm typed examples compile
   - OpenAPI: validate spec with `npx @redocly/cli lint openapi.yaml`
   - If validation fails: fix examples and re-validate before proceeding to the Report step
6. **Report** - Generate coverage summary

## Quick-Reference Examples

### Google-style Docstring (Python)
```python
def fetch_user(user_id: int, active_only: bool = True) -> dict:
    """Fetch a single user record by ID.

    Args:
        user_id: Unique identifier for the user.
        active_only: When True, raise an error for inactive users.

    Returns:
        A dict containing user fields (id, name, email, created_at).

    Raises:
        ValueError: If user_id is not a positive integer.
        UserNotFoundError: If no matching user exists.
    """
```

### NumPy-style Docstring (Python)
```python
def compute_similarity(vec_a: np.ndarray, vec_b: np.ndarray) -> float:
    """Compute cosine similarity between two vectors.

    Parameters
    ----------
    vec_a : np.ndarray
        First input vector, shape (n,).
    vec_b : np.ndarray
        Second input vector, shape (n,).

    Returns
    -------
    float
        Cosine similarity in the range [-1, 1].

    Raises
    ------
    ValueError
        If vectors have different lengths.
    """
```

### JSDoc (TypeScript)
```typescript
/**
 * Fetches a paginated list of products from the catalog.
 *
 * @param {string} categoryId - The category to filter by.
 * @param {number} [page=1] - Page number (1-indexed).
 * @param {number} [limit=20] - Maximum items per page.
 * @returns {Promise<ProductPage>} Resolves to a page of product records.
 * @throws {NotFoundError} If the category does not exist.
 *
 * @example
 * const page = await fetchProducts('electronics', 2, 10);
 * console.log(page.items);
 */
async function fetchProducts(
  categoryId: string,
  page = 1,
  limit = 20
): Promise<ProductPage> { ... }
```

## Reference Guide

Load detailed guidance based on context:

| Topic | Reference | Load When |
|-------|-----------|-----------|
| Python Docstrings | `references/python-docstrings.md` | Google, NumPy, Sphinx styles |
| TypeScript JSDoc | `references/typescript-jsdoc.md` | JSDoc patterns, TypeScript |
| FastAPI/Django API | `references/api-docs-fastapi-django.md` | Python API documentation |
| NestJS/Express API | `references/api-docs-nestjs-express.md` | Node.js API documentation |
| Coverage Reports | `references/coverage-reports.md` | Generating documentation reports |
| Documentation Systems | `references/documentation-systems.md` | Doc sites, static generators, search, testing |
| Interactive API Docs | `references/interactive-api-docs.md` | OpenAPI 3.1, portals, GraphQL, WebSocket, gRPC, SDKs |
| User Guides & Tutorials | `references/user-guides-tutorials.md` | Getting started, tutorials, troubleshooting, FAQs |

## Constraints

### MUST DO
- Ask for format preference before starting
- Detect framework for correct API doc strategy
- Document all public functions/classes
- Include parameter types and descriptions
- Document exceptions/errors
- Test code examples in documentation
- Generate coverage report

### MUST NOT DO
- Assume docstring format without asking
- Apply wrong API doc strategy for framework
- Write inaccurate or untested documentation
- Skip error documentation
- Document obvious getters/setters verbosely
- Create documentation that's hard to maintain

## Output Formats

Depending on the task, provide:
1. **Code Documentation:** Documented files + coverage report
2. **API Docs:** OpenAPI specs + portal configuration
3. **Doc Sites:** Site configuration + content structure + build instructions
4. **Guides/Tutorials:** Structured markdown with examples + diagrams

## Knowledge Reference

Google/NumPy/Sphinx docstrings, JSDoc, OpenAPI 3.0/3.1, AsyncAPI, gRPC/protobuf, FastAPI, Django, NestJS, Express, GraphQL, Docusaurus, MkDocs, VitePress, Swagger UI, Redoc, Stoplight

[Documentation](https://jeffallan.github.io/claude-skills/skills/quality/code-documenter/)