What is SKILL.md?
A markdown file that defines a Claude Code skill with instructions, triggers, and metadata.
Detailed Explanation
SKILL.md is the standard file format for defining ClaudeCodeSkill. It contains structured instructions that teach Claude how to perform a specific task, along with frontmatter metadata including trigger conditions, description, and configuration options. When placed in a skills directory (.claude/skills/ or ~/.claude/skills/), Claude automatically loads and follows the skill's instructions when triggered. The SKILL.md format is becoming a cross-platform standard, with support in Kiro, Codex CLI, and other AI coding agents.