builder

# Claude Code Builder

Expert guidance for creating Claude Code subagents, skills, slash commands, plugins, and plugin marketplaces.

## Automatic Activation

This skill automatically activates when:
- Creating or editing `.claude/agents/*.md` files
- Working with `.claude/commands/*.md` files
- Developing `skills/*/SKILL.md` files
- Configuring `.claude-plugin/plugin.json` or `marketplace.json`
- Working with files in `.claude/` directories
- Users ask "How do I create a Claude Code skill?"
- Users ask "How do I make a slash command?"
- Users mention "building a plugin" or "creating an agent"
- Discussing Claude Code extensibility and customization

## When NOT to Use This Skill

Do not use this skill for:
- General Claude Code usage questions (non-extensibility topics)
- Debugging existing user code (unless related to plugin development)
- Standard development tasks unrelated to Claude Code components
- Basic Claude Code CLI operations (use `/help` instead)
- Questions about using existing plugins (rather than creating them)

## Quick Start

### Progressive Disclosure Design Principle

Claude Code components use a three-level loading system to manage context efficiently:

1. **Metadata (name + description)** - Always in context (~100 words)
2. **Component body** - Loaded when component triggers (<5k words recommended)
3. **Bundled resources** - Loaded as needed (unlimited)

Design components to be lean in the body, delegating detailed information to bundled references. This approach keeps the context window efficient while making specialized knowledge available when needed.

### Creating a New Component

Before starting, determine which component type fits the requirements:

- **Skill**: Automatic activation based on context (preferred for most use cases)
- **Slash Command**: Quick keyboard shortcuts for common tasks
- **Subagent**: Delegatable workflows needing context isolation
- **Plugin**: Package multiple components for distribution

### Component Selection G