skill-authoring-guide

Skill Authoring Guide

Use this skill when creating or improving a reusable skill.

What Good Skills Do

• Trigger reliably from name and description — the description must be specific enough to avoid false triggers.
• Stay short in SKILL.md and move bulk detail into references/ or scripts/.
• Teach a workflow or decision pattern, not just dump background information.
• Include scripts or references only when they eliminate repeated work or prevent ambiguity.

Frontmatter Template

---
name: kebab-case-matching-directory-name
description: Use when [trigger condition]. Does [what it does]. [Optional: NOT for X.]
---

Body Format

Default to a pure Markdown body after the YAML frontmatter. Use headings such as ## Purpose, ## When to Use, ## Workflow, and ## Verification. Do not use XML-like tags such as <Purpose>, <Workflow>, or <Use_When> as normal top-level sections. XML-like tags are acceptable only when they strictly delimit nested examples, quoted input, external documents, or machine-readable prompt payloads.

Good description (specific, trigger-clear):

Use when designing or reviewing filesystem MCP access, path boundaries, allowed roots, and method allowlists.

Weak description (too broad, won't trigger reliably):

Helps with MCP things and file access.

Workflow

1. Define the job

• What specific problem does this skill solve?
• When should it trigger? (Be concrete — "when the user mentions X" or "when you're about to do Y".)
• What should it explicitly NOT handle? State the boundary.

2. Write strong frontmatter

• name must match the directory name exactly.
• description must say what the skill does AND when to use it in one sentence.

3. Keep the body lean

• SKILL.md should be readable in one focused pass — target 50–120 lines.
• Use Markdown headings for top-level structure.
• Move bulky reference material into references/.
• Move deterministic scripts (validators, init scripts) into scripts/.
• If SKILL.md exceeds 150 lines, split off the excess into a reference file.

4. Design progressive disclosure

• SKILL.md: core workflow, when to use, safety constraints.
• references/: detailed patterns, full checklists, long examples.
• scripts/: automation helpers.

5. Validate before publishing

• Check that every file path mentioned in the skill actually exists.
• Remove any references/ links that point to non-existent files.
• Verify the skill can be read in under 2 minutes.
• Test the trigger: does the description reliably route to this skill for the intended use case?

Skill Length Guide

Section	Target
Frontmatter description	1 sentence, 15–30 words
SKILL.md body	50–120 lines
Individual workflow steps	1–3 lines each
References total	as needed, not in SKILL.md

Bundled Helpers

• scripts/init_skill.py — scaffold a new skill directory
• scripts/package_skill.py — package for distribution
• scripts/quick_validate.py — check frontmatter and dead references

Use them as optional helpers if they fit your workflow.

Verification

• The name field matches the skill directory name exactly
• The description states the trigger condition and what the skill does in one sentence
• The body reads in one focused pass — within the length guide, with bulk detail moved to references
• Every file path mentioned in the skill exists; dead reference links were removed
• The trigger was tested: the description reliably routes the intended use case to this skill

Related Skill

Use hard-won-skill-extractor when the challenge is turning a hard-earned session into a reusable skill candidate.