Comprehensive guide for creating modular skills that extend Claude's capabilities with specialized knowledge and workflows.

• Skills consist of a required SKILL.md file with YAML frontmatter and markdown instructions, plus optional bundled resources (scripts, references, assets) organized by purpose and loaded progressively to minimize context bloat
• Follow a six-step creation process: understand concrete usage examples, plan reusable contents, initialize with init_skill.py, edit resources and documentation, package with package_skill.py, and iterate based on real usage
• Keep SKILL.md lean and under 500 lines by moving detailed reference material, schemas, and examples into separate files; use the description field to clearly signal when the skill triggers
• Design for self-containment: skills must work without relying on user's personal config, MCP servers, or environment-specific setup; include all necessary context directly in the skill
• Support both Claude AI (web) and Claude Code (CLI) environments, or mark CLI-only skills with compatibility: claude-code-only in frontmatter