Skill Anatomy Explorer¶

Explore the structure of a SKILL.md file interactively. Click any section block in the diagram to reveal what that section does, whether it is required, its approximate token cost, and a real example.

Open Fullscreen 9 sections · 5 required, 4 optional · 3-tier token model

What This Sim Shows¶

The explorer maps the nine standard sections of a production SKILL.md file to a color-coded diagram. Each section is tagged with:

Required vs. Optional — five sections are required for Claude Code to execute a skill reliably; four are best-practice additions
Token cost estimate — the approximate tokens each section contributes to context
Type — whether the section is structural metadata, instructional content, or a quality gate

The file tree in the top-left panel shows where SKILL.md lives relative to the other directories in a skill package (scripts/, references/, assets/).

The 3-Tier Token Model¶

The bottom strip of the sim visualizes the progressive disclosure design pattern for skills:

Tier	When Loaded	What It Contains	Cost
Tier 1 — Metadata	Every session	YAML frontmatter + H1 title	~100 tokens
Tier 2 — Instructions	On invocation	Full SKILL.md body	< 5,000 tokens
Tier 3 — Resources	On demand	Files in `references/` and `assets/`	As needed

This design keeps skills lightweight in the global skill registry while making full workflow detail available exactly when Claude needs it.

Sections at a Glance¶

Section	Color	Required	Tokens
YAML Frontmatter	Blue	Yes	~100
H1 Title	White	Yes	~5
Overview / Purpose	Purple	Yes	~80
When to Activate	Green	Yes	~120
Workflow Steps	Orange	Yes	~1,200
Output Files Summary	Blue	Yes	~150
Example Session	Purple	No	~300
Common Pitfalls	Orange	No	~200
Quality Scoring Rubric	Green	No	~400

Design principle

The five required sections are the minimum contract between the skill and Claude Code. The four optional sections are what separate a working skill from a production-quality skill. Add them when the skill will be used by others or invoked frequently.