Skill Builder
Skill Builder
What This Skill Does
Creates production-ready Claude Code Skills with proper YAML frontmatter, progressive disclosure architecture, and complete file/folder structure. This skill guides you through building skills that Claude can autonomously discover and use across all surfaces (Claude.ai, Claude Code, SDK, API).
Prerequisites
- Claude Code 2.0+ or Claude.ai with Skills support
- Basic understanding of Markdown and YAML
- Text editor or IDE
Quick Start
Creating Your First Skill
# 1. Create skill directory (MUST be at top level, NOT in subdirectories!)
mkdir -p ~/.claude/skills/my-first-skill
# 2. Create SKILL.md with proper format
cat > ~/.claude/skills/my-first-skill/SKILL.md << 'EOF'
---
name: "My First Skill"
description: "Brief description of what this skill does and when Claude should use it. Maximum 1024 characters."
---
# My First Skill
## What This Skill Does
[Your instructions here]
## Quick Start
[Basic usage]
EOF
# 3. Verify skill is detected
# Restart Claude Code or refresh Claude.ai
Complete Specification
📋 YAML Frontmatter (REQUIRED)
Every SKILL.md must start with YAML frontmatter containing exactly two required fields:
---
name: "Skill Name" # REQUIRED: Max 64 chars
description: "What this skill does # REQUIRED: Max 1024 chars
and when Claude should use it." # Include BOTH what & when
---
Field Requirements
name (REQUIRED):
- Type: String
- Max Length: 64 characters
- Format: Human-friendly display name
- Usage: Shown in skill lists, UI, and loaded into Claude's system prompt
- Best Practice: Use Title Case, be concise and descriptive
- Examples:
- ✅ "API Documentation Generator"
- ✅ "React Component Builder"
- ✅ "Database Schema Designer"
- ❌ "skill-1" (not descriptive)
- ❌ "This is a very long skill name that exceeds sixty-four characters" (too long)
description (REQUIRED):
- Type: String
- Max Length: 1024 characters
- Format: Plain text or minimal markdown
- Content: MUST include:
- What the skill does (functionality)
- When Claude should invoke it (trigger conditions)
- Usage: Loaded into Claude's system prompt for autonomous matching
- Best Practice: Front-load key trigger words, be specific about use cases
- Examples:
- ✅ "Generate OpenAPI 3.0 documentation from Express.js routes. Use when creating API docs, documenting endpoints, or building API specifications."
- ✅ "Create React functional components with TypeScript, hooks, and tests. Use when scaffolding new components or converting class components."
- ❌ "A comprehensive guide to API documentation" (no "when" clause)
- ❌ "Documentation tool" (too vague)
YAML Formatting Rules
---
# ✅ CORRECT: Simple string
name: "API Builder"
description: "Creates REST APIs with Express and TypeScript."
# ✅ CORRECT: Multi-line description
name: "Full-Stack Generator"
description: "Generates full-stack applications with React frontend and Node.js backend. Use when starting new projects or scaffolding applications."
# ✅ CORRECT: Special characters quoted
name: "JSON:API Builder"
description: "Creates JSON:API compliant endpoints: pagination, filtering, relationships."
# ❌ WRONG: Missing quotes with special chars
name: API:Builder # YAML parse error!
# ❌ WRONG: Extra fields (ignored but discouraged)
name: "My Skill"
description: "My description"
version: "1.0.0" # NOT part of spec
author: "Me" # NOT part of spec
tags: ["dev", "api"] # NOT part of spec
---
Critical: Only name and description are used by Claude. Additional fields are ignored.
📂 Directory Structure
Minimal Skill (Required)
~/.claude/skills/ # Personal skills location
└── my-skill/ # Skill directory (MUST be at top level!)
└── SKILL.md # REQUIRED: Main skill file
IMPORTANT: Skills MUST be directly under ~/.claude/skills/[skill-name]/.
Claude Code does NOT support nested subdirectories or namespaces!
Full-Featured Skill (Recommended)
~/.claude/skills/
└── my-skill/ # Top-level skill directory
├── SKILL.md # REQUIRED: Main skill file
├── README.md # Optional: Human-readable docs
├── scripts/ # Optional: Executable scripts
│ ├── setup.sh
│ ├── validate.js
│ └── deploy.py
├── resources/ # Optional: Supporting files
│ ├── templates/
│ │ ├── api-template.js
│ │ └── component.tsx
│ ├── examples/
│ │ └── sample-output.json
│ └── schemas/
│ └── config-schema.json
└── docs/ # Optional: Additional documentation
├── ADVANCED.md
├── TROUBLESHOOTING.md
└── API_REFERENCE.md
Skills Locations
Personal Skills (available across all projects):
~/.claude/skills/
└── [your-skills]/
- Path:
~/.claude/skills/or$HOME/.claude/skills/ - Scope: Available in all projects for this user
- Version Control: NOT committed to git (outside repo)
- Use Case: Personal productivity tools, custom workflows
Project Skills (team-shared, version controlled):
<project-root>/.claude/skills/
└── [team-skills]/
- Path:
.claude/skills/in project root - Scope: Available only in this project
- Version Control: SHOULD be committed to git
- Use Case: Team workflows, project-specific tools, shared knowledge
🎯 Progressive Disclosure Architecture
Claude Code uses a 3-level progressive disclosure system to scale to 100+ skills without context penalty:
Level 1: Metadata (Name + Description)
Loaded: At Claude Code startup, always Size: ~200 chars per skill Purpose: Enable autonomous skill matching Context: Loaded into system prompt for ALL skills
---
name: "API Builder" # 11 chars
description: "Creates REST APIs..." # ~50 chars
---
# Total: ~61 chars per skill
# 100 skills = ~6KB context (minimal!)
Level 2: SKILL.md Body
Loaded: When skill is triggered/matched Size: ~1-10KB typically Purpose: Main instructions and procedures Context: Only loaded for ACTIVE skills
# API Builder
## What This Skill Does
[Main instructions - loaded only when skill is active]
## Quick Start
[Basic procedures]
## Step-by-Step Guide
[Detailed instructions]
Level 3+: Referenced Files
Loaded: On-demand as Claude navigates Size: Variable (KB to MB) Purpose: Deep reference, examples, schemas Context: Loaded only when Claude accesses specific files
# In SKILL.md
See [Advanced Configuration](docs/ADVANCED.md) for complex scenarios.
See [API Reference](docs/API_REFERENCE.md) for complete documentation.
Use template: `resources/templates/api-template.js`
# Claude will load these files ONLY if needed
Benefit: Install 100+ skills with ~6KB context. Only active skill content (1-10KB) enters context.
📝 SKILL.md Content Structure
Recommended 4-Level Structure
---
name: "Your Skill Name"
description: "What it does and when to use it"
---
# Your Skill Name
## Level 1: Overview (Always Read First)
Brief 2-3 sentence description of the skill.
## Prerequisites
- Requirement 1
- Requirement 2
## What This Skill Does
1. Primary function
2. Secondary function
3. Key benefit
---
## Level 2: Quick Start (For Fast Onboarding)
### Basic Usage
```bash
# Simplest use case
command --option value
Common Scenarios
- Scenario 1: How to...
- Scenario 2: How to...
Level 3: Detailed Instructions (For Deep Work)
Step-by-Step Guide
Step 1: Initial Setup
# Commands
Expected output:
Success message
Step 2: Configuration
- Configuration option 1
- Configuration option 2
Step 3: Execution
- Run the main command
- Verify results
Advanced Options
Option 1: Custom Configuration
# Advanced usage
Option 2: Integration
# Integration steps
Level 4: Reference (Rarely Needed)
Troubleshooting
Issue: Common Problem
Symptoms: What you see Cause: Why it happens Solution: How to fix
# Fix command
Issue: Another Problem
Solution: Steps to resolve
Complete API Reference
See API_REFERENCE.md
Examples
See examples/
Related Skills
Resources
---
### 🎨 Content Best Practices
#### Writing Effective Descriptions
**Front-Load Keywords**:
```yaml
# ✅ GOOD: Keywords first
description: "Generate TypeScript interfaces from JSON schema. Use when converting schemas, creating types, or building API clients."
# ❌ BAD: Keywords buried
description: "This skill helps developers who need to work with JSON schemas by providing a way to generate TypeScript interfaces."
Include Trigger Conditions:
# ✅ GOOD: Clear "when" clause
description: "Debug React performance issues using Chrome DevTools. Use when components re-render unnecessarily, investigating slow updates, or optimizing bundle size."
# ❌ BAD: No trigger conditions
description: "Helps with React performance debugging."
Be Specific:
# ✅ GOOD: Specific technologies
description: "Create Express.js REST endpoints with Joi validation, Swagger docs, and Jest tests. Use when building new APIs or adding endpoints."
# ❌ BAD: Too generic
description: "Build API endpoints with proper validation and testing."
Progressive Disclosure Writing
Keep Level 1 Brief (Overview):
## What This Skill Does
Creates production-ready React components with TypeScript, hooks, and tests in 3 steps.
Level 2 for Common Paths (Quick Start):
## Quick Start
```bash
# Most common use case (80% of users)
generate-component MyComponent
**Level 3 for Details** (Step-by-Step):
```markdown
## Step-by-Step Guide
### Creating a Basic Component
1. Run generator
2. Choose template
3. Customize options
[Detailed explanations]
Level 4 for Edge Cases (Reference):
## Advanced Configuration
For complex scenarios like HOCs, render props, or custom hooks, see [ADVANCED.md](docs/ADVANCED.md).
🛠️ Adding Scripts and Resources
Scripts Directory
Purpose: Executable scripts that Claude can run
Location: scripts/ in skill directory
Usage: Referenced from SKILL.md
Example:
# In skill directory
scripts/
├── setup.sh # Initialization script
├── validate.js # Validation logic
├── generate.py # Code generation
└── deploy.sh # Deployment script
Reference from SKILL.md:
## Setup
Run the setup script:
```bash
./scripts/setup.sh
Validation
Validate your configuration:
node scripts/validate.js config.json
#### Resources Directory
**Purpose**: Templates, examples, schemas, static files
**Location**: `resources/` in skill directory
**Usage**: Referenced or copied by scripts
Example:
```bash
resources/
├── templates/
│ ├── component.tsx.template
│ ├── test.spec.ts.template
│ └── story.stories.tsx.template
├── examples/
│ ├── basic-example/
│ ├── advanced-example/
│ └── integration-example/
└── schemas/
├── config.schema.json
└── output.schema.json
Reference from SKILL.md:
## Templates
Use the component template:
```bash
cp resources/templates/component.tsx.template src/components/MyComponent.tsx
Examples
See working examples in resources/examples/:
basic-example/- Simple componentadvanced-example/- With hooks and context
---
### 🔗 File References and Navigation
Claude can navigate to referenced files automatically. Use these patterns:
#### Markdown Links
```markdown
See [Advanced Configuration](docs/ADVANCED.md) for complex scenarios.
See [Troubleshooting Guide](docs/TROUBLESHOOTING.md) if you encounter errors.
Relative File Paths
Use the template located at `resources/templates/api-template.js`
See examples in `resources/examples/basic-usage/`
Inline File Content
## Example Configuration
See `resources/examples/config.json`:
```json
{
"option": "value"
}
**Best Practice**: Keep SKILL.md lean (~2-5KB). Move lengthy content to separate files and reference them. Claude will load only what's needed.
---
### ✅ Validation Checklist
Before publishing a skill, verify:
**YAML Frontmatter**:
- [ ] Starts with `---`
- [ ] Contains `name` field (max 64 chars)
- [ ] Contains `description` field (max 1024 chars)
- [ ] Description includes "what" and "when"
- [ ] Ends with `---`
- [ ] No YAML syntax errors
**File Structure**:
- [ ] SKILL.md exists in skill directory
- [ ] Directory is DIRECTLY in `~/.claude/skills/[skill-name]/` or `.claude/skills/[skill-name]/`
- [ ] Uses clear, descriptive directory name
- [ ] **NO nested subdirectories** (Claude Code requires top-level structure)
**Content Quality**:
- [ ] Level 1 (Overview) is brief and clear
- [ ] Level 2 (Quick Start) shows common use case
- [ ] Level 3 (Details) provides step-by-step guide
- [ ] Level 4 (Reference) links to advanced content
- [ ] Examples are concrete and runnable
- [ ] Troubleshooting section addresses common issues
**Progressive Disclosure**:
- [ ] Core instructions in SKILL.md (~2-5KB)
- [ ] Advanced content in separate docs/
- [ ] Large resources in resources/ directory
- [ ] Clear navigation between levels
**Testing**:
- [ ] Skill appears in Claude's skill list
- [ ] Description triggers on relevant queries
- [ ] Instructions are clear and actionable
- [ ] Scripts execute successfully (if included)
- [ ] Examples work as documented
---
## Skill Builder Templates
### Template 1: Basic Skill (Minimal)
```markdown
---
name: "My Basic Skill"
description: "One sentence what. One sentence when to use."
---
# My Basic Skill
## What This Skill Does
[2-3 sentences describing functionality]
## Quick Start
```bash
# Single command to get started
Step-by-Step Guide
Step 1: Setup
[Instructions]
Step 2: Usage
[Instructions]
Step 3: Verify
[Instructions]
Troubleshooting
- Issue: Problem description
- Solution: Fix description
### Template 2: Intermediate Skill (With Scripts)
```markdown
---
name: "My Intermediate Skill"
description: "Detailed what with key features. When to use with specific triggers: scaffolding, generating, building."
---
# My Intermediate Skill
## Prerequisites
- Requirement 1
- Requirement 2
## What This Skill Does
1. Primary function
2. Secondary function
3. Integration capability
## Quick Start
```bash
./scripts/setup.sh
./scripts/generate.sh my-project
Configuration
Edit config.json:
{
"option1": "value1",
"option2": "value2"
}
Step-by-Step Guide
Basic Usage
[Steps for 80% use case]
Advanced Usage
[Steps for complex scenarios]
Available Scripts
scripts/setup.sh- Initial setupscripts/generate.sh- Code generationscripts/validate.sh- Validation
Resources
- Templates:
resources/templates/ - Examples:
resources/examples/
Troubleshooting
[Common issues and solutions]
### Template 3: Advanced Skill (Full-Featured)
```markdown
---
name: "My Advanced Skill"
description: "Comprehensive what with all features and integrations. Use when [trigger 1], [trigger 2], or [trigger 3]. Supports [technology stack]."
---
# My Advanced Skill
## Overview
[Brief 2-3 sentence description]
## Prerequisites
- Technology 1 (version X+)
- Technology 2 (version Y+)
- API keys or credentials
## What This Skill Does
1. **Core Feature**: Description
2. **Integration**: Description
3. **Automation**: Description
---
## Quick Start (60 seconds)
### Installation
```bash
./scripts/install.sh
First Use
./scripts/quickstart.sh
Expected output:
✓ Setup complete
✓ Configuration validated
→ Ready to use
Configuration
Basic Configuration
Edit config.json:
{
"mode": "production",
"features": ["feature1", "feature2"]
}
Advanced Configuration
Step-by-Step Guide
1. Initial Setup
[Detailed steps]
2. Core Workflow
[Main procedures]
3. Integration
[Integration steps]
Advanced Features
Feature 1: Custom Templates
./scripts/generate.sh --template custom
Feature 2: Batch Processing
./scripts/batch.sh --input data.json
Feature 3: CI/CD Integration
See CI/CD Guide
Scripts Reference
| Script | Purpose | Usage |
|---|---|---|
install.sh |
Install dependencies | ./scripts/install.sh |
generate.sh |
Generate code | ./scripts/generate.sh [name] |
validate.sh |
Validate output | ./scripts/validate.sh |
deploy.sh |
Deploy to environment | ./scripts/deploy.sh [env] |
Resources
Templates
resources/templates/basic.template- Basic templateresources/templates/advanced.template- Advanced template
Examples
resources/examples/basic/- Simple exampleresources/examples/advanced/- Complex exampleresources/examples/integration/- Integration example
Schemas
resources/schemas/config.schema.json- Configuration schemaresources/schemas/output.schema.json- Output validation
Troubleshooting
Issue: Installation Failed
Symptoms: Error during install.sh
Cause: Missing dependencies
Solution:
# Install prerequisites
npm install -g required-package
./scripts/install.sh --force
Issue: Validation Errors
Symptoms: Validation script fails Solution: See Troubleshooting Guide
API Reference
Complete API documentation: API_REFERENCE.md
Related Skills
Resources
Created: 2025-10-19 Category: Advanced Difficulty: Intermediate Estimated Time: 15-30 minutes
---
## Examples from the Wild
### Example 1: Simple Documentation Skill
```markdown
---
name: "README Generator"
description: "Generate comprehensive README.md files for GitHub repositories. Use when starting new projects, documenting code, or improving existing READMEs."
---
# README Generator
## What This Skill Does
Creates well-structured README.md files with badges, installation, usage, and contribution sections.
## Quick Start
```bash
# Answer a few questions
./scripts/generate-readme.sh
# README.md created with:
# - Project title and description
# - Installation instructions
# - Usage examples
# - Contribution guidelines
Customization
Edit sections in resources/templates/sections/ before generating.
### Example 2: Code Generation Skill
```markdown
---
name: "React Component Generator"
description: "Generate React functional components with TypeScript, hooks, tests, and Storybook stories. Use when creating new components, scaffolding UI, or following component architecture patterns."
---
# React Component Generator
## Prerequisites
- Node.js 18+
- React 18+
- TypeScript 5+
## Quick Start
```bash
./scripts/generate-component.sh MyComponent
# Creates:
# - src/components/MyComponent/MyComponent.tsx
# - src/components/MyComponent/MyComponent.test.tsx
# - src/components/MyComponent/MyComponent.stories.tsx
# - src/components/MyComponent/index.ts
Step-by-Step Guide
1. Run Generator
./scripts/generate-component.sh ComponentName
2. Choose Template
- Basic: Simple functional component
- With State: useState hooks
- With Context: useContext integration
- With API: Data fetching component
3. Customize
Edit generated files in src/components/ComponentName/
Templates
See resources/templates/ for available component templates.
---
## Learn More
### Official Resources
- [Anthropic Agent Skills Documentation](https://docs.claude.com/en/docs/agents-and-tools/agent-skills)
- [GitHub Skills Repository](https://github.com/anthropics/skills)
- [Claude Code Documentation](https://docs.claude.com/en/docs/claude-code)
### Community
- [Skills Marketplace](https://github.com/anthropics/skills) - Browse community skills
- [Anthropic Discord](https://discord.gg/anthropic) - Get help from community
### Advanced Topics
- Multi-file skills with complex navigation
- Skills that spawn other skills
- Integration with MCP tools
- Dynamic skill generation
---
**Created**: 2025-10-19
**Version**: 1.0.0
**Maintained By**: agentic-flow team
**License**: MIT