Library › Book 1 › Anatomy of a SKILL.md File
Anatomy of a SKILL.md File
2.1🔒The Two-Part StructureEvery agent skill is a single file named SKILL.md with two sections: a YAML frontmatter header (metadata controlling discovery and…
2.2🔒YAML Frontmatter: The Selection Signalname (required, max 64 characters) is the unique identifier and invocation command (/my-skill). Lowercase letters, numbers, and hyphens…
2.3🔒Markdown Body: The Execution InstructionsThe body is what the agent reads when the skill is invoked. Structure it for an AI agent reader, not a human: agents want structured…
2.4🔒The Generated playwright-cli Skill: A Case StudyThe SKILL.md that playwright-cli install --skills generates is an exemplary CLI-wrapping skill: ~100 lines, zero bundled resources. The CLI…
2.5🔒Bundled ResourcesSkills can include directories alongside SKILL.md for complex needs:
2.6🔒How the Agent Uses the Skill at RuntimeThe complete flow for "Go to example.com and take a screenshot":
2.7🔒Key Takeaways- A SKILL.md has two parts: YAML frontmatter (metadata) and markdown body (instructions) - The description field is the selection signal…
2.8🔒Q&ASelf-Assessment Quiz1. What are the two required fields in SKILL.md frontmatter? 2. Why is the description field the most important? 3. What does…
2.9🔒Exercises[Beginner] Exercise 2.1: Write a SKILL.md frontmatter for a hypothetical database-backup skill with appropriate name, description, and…
2.10🔒Career Translation- Authored SKILL.md files following the two-part architecture (YAML frontmatter for selection metadata, markdown body for execution…
2.11🔒Q&AInterview Depth CheckPrompt: You must write a SKILL.md for a database migration tool with 15 CLI commands. How do you structure it under 500 lines? A strong…