CLAUDE.md Writer

A skill for creating and optimizing CLAUDE.md files following official Anthropic best practices (2026-01).

When to Use This Skill

• Creating a new CLAUDE.md for a project
• Reviewing/auditing an existing CLAUDE.md
• Optimizing documentation for better Claude Code performance
• User asks about CLAUDE.md best practices

Golden Rule

Para cada línea, preguntá: "¿Eliminar esto causaría que Claude cometa errores?" Si no, eliminalo. CLAUDE.md inflados causan que Claude ignore instrucciones.

"Think of CLAUDE.md as the 'unwritten knowledge' in your codebase"

Quick Tools

• /init - Genera CLAUDE.md inicial basado en la estructura del proyecto
• # key - Agregar instrucciones dinámicamente durante la sesión

@import Syntax

CLAUDE.md puede importar otros archivos:

See @README.md for overview and @package.json for commands.
Git workflow: @docs/git-instructions.md

Reference Documentation

For detailed best practices, read: docs/claude-md-best-practices.md

What to Include vs Exclude

✅ Include	❌ Exclude
Bash commands Claude can't guess	Anything Claude can figure out by reading code
Code style rules that differ from defaults	Standard language conventions
Testing instructions and preferred test runners	Detailed API docs (link instead)
Repository etiquette (branch naming, PR)	Information that changes frequently
Architectural decisions specific to project	Long explanations or tutorials
Developer environment quirks (env vars)	File-by-file descriptions
Common gotchas or non-obvious behaviors	Self-evident practices

CLAUDE.md vs Skills

CLAUDE.md	Skills
Reglas amplias que aplican siempre	Conocimiento de dominio solo relevante a veces
Code style y workflow	Workflows especializados reutilizables
Convenciones del repo	Info que cambia por contexto
Se carga en cada sesión	Se cargan on-demand

Usage Modes

El skill acepta argumentos para diferentes flujos:

Invocación	Comportamiento
/claude-md-writer	Proceso completo: analizar proyecto → escribir/mejorar CLAUDE.md
/claude-md-writer actualiza con la sesión	Extraer info relevante de la sesión actual y agregar a CLAUDE.md
/claude-md-writer agrega regla: [descripción]	Agregar una regla específica con el formato correcto
/claude-md-writer revisa y optimiza	Auditar CLAUDE.md existente, eliminar redundancias, mejorar énfasis
/claude-md-writer convierte a skill	Identificar contenido que debería ser skill y extraerlo

Content Triage

Antes de agregar contenido a CLAUDE.md, evaluar:

Si el contenido es...	Entonces...
Regla que aplica a TODAS las tareas	✅ Agregar a CLAUDE.md
Domain knowledge específico	🔄 Sugerir crear skill con /skill-creator
Workflow que solo aplica a veces	🔄 Sugerir crear skill
Info que cambia frecuentemente	❌ No agregar, linkear a docs

Detectar candidatos a Skill

Si el usuario quiere agregar info que cumple estos criterios, sugerir skill:

• "Cuando trabajes con X..." (condicional)
• "Para tareas de tipo Y..." (específico)
• "Si estás haciendo Z..." (situacional)
• Workflows con muchos pasos
• Conocimiento de dominio especializado

Respuesta sugerida:

Esta información parece ser domain knowledge/workflow específico que no aplica a todas las tareas. Te sugiero crear un skill separado usando /skill-creator o document-skills:skill-creator. Así se carga on-demand sin inflar cada sesión.

Process

Step 1: Analyze the Project

Before writing, gather information:

# Check project type and structure
ls -la
cat package.json 2>/dev/null || cat pom.xml 2>/dev/null || cat Cargo.toml 2>/dev/null

# Find existing documentation
ls -la docs/ 2>/dev/null
ls -la README.md 2>/dev/null

Identify:

• Tech stack (language, framework, build tools)
• Project structure (monorepo, single app, library)
• Existing documentation to reference

Step 2: Apply the Three Dimensions

Every CLAUDE.md must address:

Dimension	Question to Answer
WHAT	What is this project? Tech stack? Structure?
WHY	Why does it exist? What problem does it solve?
HOW	How do I work on it? Commands? Workflows?

Triage Check

Para cada pieza de información, preguntar:

1. ¿Aplica a TODAS las tareas en este repo? → CLAUDE.md
2. ¿Solo aplica a ciertos tipos de tareas? → Skill
3. ¿Cambia frecuentemente? → Link externo

Step 3: Write Following Best Practices

Length: Keep under 200 lines (ideal ~100 lines)

Structure (in order):

1. Repository Overview (1 paragraph)
2. Why This Exists (purpose, users)
3. Quick Start & Commands (bash with descriptions)
4. Architecture Overview (key patterns)
5. Key Development Rules (with emphasis)
6. References (links to detailed docs)

Emphasis for Critical Rules:

- **CRITICAL**: [Never violate this]
- **IMPORTANT**: [Always do this]
- **YOU MUST**: [Mandatory action]

Progressive Disclosure:

• Use file references instead of code snippets
• Link to external docs for detailed topics
• Keep CLAUDE.md focused on universal instructions

Step 4: Verify with Checklist

Before finalizing, verify:

• Under 200 lines?
• Passes Golden Rule? (each line prevents mistakes)
• Has WHAT, WHY, HOW sections?
• Critical rules have emphasis (CRITICAL/IMPORTANT)?
• Code snippets replaced with file references?
• Bash commands have descriptions?
• References external docs for detailed topics?
• No styling rules that should be in linters?
• Domain-specific content moved to skills?

Template

# CLAUDE.md

This file provides guidance to Claude Code when working with this repository.

## Repository Overview

[One paragraph: what this project is, tech stack, main purpose]

## Why This Exists

[What problem it solves, who uses it, business context]

## Quick Start & Commands

\`\`\`bash
npm ci        # Install dependencies
npm start     # Start dev server
npm test      # Run tests
npm run build # Production build
\`\`\`

> **Note**: [Any important setup notes, env files, postinstall behavior]

## Architecture Overview

[Key patterns, folder structure, main concepts - keep brief]

## Key Development Rules

- **CRITICAL**: [Most important rule that must never be violated]
- **IMPORTANT**: [Second most important rule]
- [Other rules...]

## References

- `/docs/` - Detailed documentation
- `README.md` - Project readme

Anti-Patterns to Avoid

Anti-Pattern	Why It's Bad	Do This Instead
Code snippets	Become stale, waste tokens	Use file:line references
Styling rules	LLM is slow for deterministic tasks	Configure linters
Kitchen sink	Dilutes instruction effectiveness	Keep < 200 lines
No emphasis	Critical rules same weight as minor	Use CRITICAL/IMPORTANT
Auto-generated	Misses project nuances	Manually craft
Domain knowledge	Inflates every session	Move to skills