Comprehensive guide for creating and managing skills in Claude Code with auto-activation system, following Anthropic's official best practices including the 500-line rule and progressive disclosure pattern.
Philosophy Change (2025-10-27): We moved away from blocking PreToolUse for Sentry/error handling. Instead, use gentle post-response reminders that don't block workflow but maintain code quality awareness.
✅ Keep SKILL.md under 500 lines ✅ Use progressive disclosure with reference files ✅ Add table of contents to reference files > 100 lines ✅ Write detailed description with trigger keywords ✅ Test with 3+ real scenarios before documenting ✅ Iterate based on actual usage
Create and manage Claude Code skills following Anthropic best practices. Use when creating new skills, modifying skill-rules.json, understanding trigger patterns, working with hooks, debugging skill activation, or implementing progressive disclosure. Covers skill structure, YAML frontmatter, trigger types (keywords, intent patterns, file paths, content patterns), enforcement levels (block, suggest, warn), hook mechanisms (UserPromptSubmit, PreToolUse), session tracking, and the 500-line rule. Source: chacha95/advanced-harness.