Claude Code Skills: The Complete Guide to Extending Claude's Capabilities

Claude skills are packaged instructions that extend Claude’s capabilities beyond its base knowledge. Think of them as “instruction manuals” that teach Claude how to properly use specific tools, frameworks, and workflows.

In December 2025, Anthropic released the Agent Skills specification as an open standard. OpenAI adopted the same format for Codex CLI, making skills portable across multiple AI coding assistants.

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What Are Claude Skills?

A skill is a folder containing a SKILL.md file with YAML frontmatter and markdown instructions. When you invoke a skill (or Claude detects it’s relevant), the instructions load into context and guide Claude’s behavior.

Basic structure:

my-skill/
├── SKILL.md           # Required: instructions + metadata
├── templates/         # Optional: template files
├── examples/          # Optional: example outputs
└── scripts/           # Optional: helper scripts

Example SKILL.md:

---
name: code-reviewer
description: Review code for bugs, security issues, and best practices.
  Use when reviewing PRs or auditing code quality.
---

When reviewing code, analyze:

1. **Security** - SQL injection, XSS, authentication flaws
2. **Performance** - N+1 queries, memory leaks, blocking calls
3. **Maintainability** - Naming, complexity, documentation
4. **Testing** - Coverage gaps, edge cases, assertions

For each issue found, provide:
- Severity (Critical/High/Medium/Low)
- Line number and file
- Recommended fix with code example

---

How Skills Work

Skills have two invocation modes:

Mode	Trigger	Use Case
Manual	You type /skill-name	Explicit workflows like /deploy
Automatic	Claude decides based on context	Claude loads when your request matches the skill description

Skill descriptions are always loaded so Claude knows what’s available. Full instructions only load when invoked, keeping context costs low.

Control invocation behavior:

---
name: deploy-production
description: Deploy to production environment
disable-model-invocation: true  # Only manual /deploy works
---

---
name: legacy-system-context
description: Background knowledge about our legacy systems
user-invocable: false  # Hidden from /menu, Claude loads when needed
---

---

Installing Skills

Personal Skills (All Projects)

~/.claude/skills/my-skill/SKILL.md

Project Skills (Current Project Only)

.claude/skills/my-skill/SKILL.md

From GitHub Repositories

npx skills add remotion-dev/skills
npx skills add anthropics/skills

Cross-Platform Compatibility

Skills work across multiple AI coding assistants:

Tool	Project Path	Global Path
Claude Code	.claude/skills/	~/.claude/skills/
Codex CLI	.codex/skills/	~/.codex/skills/
Cursor	.cursor/skills/	~/.cursor/skills/
Gemini CLI	.gemini/skills/	~/.gemini/skills/

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Official Anthropic Skills

Anthropic maintains production-grade skills in their official repository.

Document Skills

These power Claude’s document capabilities:

Skill	Purpose
docx	Create, edit, and analyze Word documents with tracked changes
pdf	Extract text/tables, create PDFs, merge/split, handle forms
pptx	Create PowerPoint presentations with layouts and charts
xlsx	Create Excel spreadsheets with formulas and data analysis

Creative & Design Skills

Skill	Purpose
algorithmic-art	Generate art using p5.js with seeded randomness and flow fields
canvas-design	Design visual art in PNG and PDF formats
frontend-design	Avoid generic “AI slop” aesthetics; works well with React + Tailwind
slack-gif-creator	Create animated GIFs optimized for Slack size constraints

Development Skills

Skill	Purpose
mcp-builder	Guide for creating high-quality MCP servers
webapp-testing	Test local web applications using Playwright
web-artifacts-builder	Build HTML artifacts using React, Tailwind, and shadcn/ui

Meta Skills

Skill	Purpose
skill-creator	Interactive guide for building your own skills

Install official skills:

npx skills add anthropics/skills

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Remotion: AI Video Creation

Remotion skills turn Claude into a video creation expert. With one command, Claude understands Remotion’s React-based video framework.

Install:

npx skills add remotion-dev/skills

Or during project creation:

bun create video  # Select skills option when prompted

What you can do:

• Create videos from natural language descriptions
• Add captions, transitions, and animations
• Edit existing video projects
• Generate motion graphics

Claude uses Remotion skills alongside FFmpeg and Whisper for automated video editing workflows.

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Company-Sponsored Skills

Major tech companies maintain official skills for their platforms.

Vercel Engineering

npx skills add vercel/skills

• react-best-practices - React patterns and guidelines
• vercel-deploy - Project deployment automation
• web-design-guidelines - Design standards reference

Cloudflare

npx skills add cloudflare/skills

• agents-sdk - Build stateful AI agents with scheduling
• durable-objects - Stateful coordination primitives
• web-perf - Core Web Vitals auditing
• wrangler - Worker deployment and management

Stripe

npx skills add stripe/skills

• stripe-best-practices - Integration guidelines
• upgrade-stripe - Version migration assistance

Trail of Bits Security

17 specialized security skills:

• Smart contract auditing
• CodeQL and Semgrep analysis
• Vulnerability detection
• Property-based testing
• Differential code review

Sentry

npx skills add getsentry/skills

• Code review automation
• Bug detection patterns
• PR workflow assistance

Database Platforms

• Neon - PostgreSQL best practices
• Supabase - Backend integration patterns
• Tinybird - Real-time analytics datasources

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Community Skills Worth Installing

Obra Superpowers

20+ battle-tested skills for development workflows:

npx skills add nicholascharriere/claude-superpowers

Commands include:

• /brainstorm - Structured ideation
• /write-plan - Implementation planning
• /execute-plan - Step-by-step execution
• /tdd - Test-driven development workflow

Context Engineering Skills

Specialized skills for managing Claude’s context:

• Context fundamentals
• Degradation patterns
• Compression techniques
• Multi-agent architectures

Platform-Specific Skills

Skill	Purpose	Install
ios-simulator	iOS app building and testing	Community
playwright	Browser automation	Community
terraform	Infrastructure as code	Community
d3js	Data visualizations	Community
three-js	3D graphics and WebGL	Community

---

Creating Your Own Skills

Basic Template

---
name: my-workflow
description: Describe what this skill does and when Claude should use it.
  Be specific so Claude knows when to auto-load it.
---

# My Workflow

## Context
[Background information Claude needs]

## Steps
1. First action
2. Second action
3. Third action

## Examples
- Example input -> expected output

## Guidelines
- Rule 1
- Rule 2

Advanced Frontmatter

---
name: safe-reader
description: Read-only code exploration
allowed-tools: Read, Grep, Glob  # Restrict tool access
context: fork                     # Run in isolated subagent
agent: Explore                    # Use Explore subagent type
---

Dynamic Context Injection

Run shell commands before sending instructions to Claude:

---
name: pr-review
description: Review the current pull request
---

## Current PR Context
- Diff: !`gh pr diff`
- Comments: !`gh pr view --comments`
- Files changed: !`gh pr diff --name-only`

## Review Instructions
[Your review guidelines here]

The !command“ syntax runs at invocation time, injecting real data into the skill.

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Skill Discovery

SkillsMP Marketplace

Browse 71,000+ skills with filtering by category, author, and popularity. Compatible with Claude Code, Codex CLI, and ChatGPT.

Awesome Lists

• awesome-claude-skills - Curated community collection
• awesome-agent-skills - Cross-platform skills
• VoltAgent collection - Additional community skills

Convert Documentation to Skills

Skill_Seekers converts documentation websites into Claude skills automatically.

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Recommended Starter Kit

For most developers, start with these:

# Official Anthropic skills (documents, design, development)
npx skills add anthropics/skills

# Remotion for video creation
npx skills add remotion-dev/skills

# Your platform of choice
npx skills add vercel/skills
npx skills add cloudflare/skills
npx skills add stripe/skills

Then create project-specific skills in .claude/skills/ for your team’s workflows:

• Coding standards
• PR review checklist
• Deployment procedures
• Domain-specific knowledge

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Troubleshooting

Skill Not Loading

1. Check the description matches your request
2. Verify skill exists: ask Claude “What skills are available?”
3. Try manual invocation: /skill-name
4. Run /context to check if skills exceeded the character budget

Skill Loads Too Often

1. Make the description more specific
2. Add disable-model-invocation: true for manual-only

Context Budget

Skills share a 15,000 character budget by default. Increase with:

export SLASH_COMMAND_TOOL_CHAR_BUDGET=30000

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The Future of Skills

Agent Skills represent a shift in how we extend AI capabilities. Instead of fine-tuning or complex integrations, you write markdown instructions that any compatible AI agent can follow.

The open standard means:

• Portability - Same skill works in Claude Code, Codex, Cursor, Gemini CLI
• Composability - Skills can reference and build on each other
• Community - Share skills across teams and companies

Skills are the plugin system for the AI agent era.