create-skill

<essential_principles>

How Skills Work

Skills are modular, filesystem-based capabilities that provide domain expertise on demand. This skill teaches how to create effective skills.

1. Skills Are Prompts

All prompting best practices apply. Be clear, be direct, use XML structure. Assume Claude is smart - only add context Claude doesn't have.

2. SKILL.md Is Always Loaded

When a skill is invoked, Claude reads SKILL.md. Use this guarantee:

• Essential principles go in SKILL.md (can't be skipped)
• Workflow-specific content goes in workflows/
• Reusable knowledge goes in references/

3. Router Pattern for Complex Skills

skill-name/
├── SKILL.md              # Router + principles
├── workflows/            # Step-by-step procedures (FOLLOW)
├── references/           # Domain knowledge (READ)
├── templates/            # Output structures (COPY + FILL)
└── scripts/              # Reusable code (EXECUTE)

SKILL.md asks "what do you want to do?" → routes to workflow → workflow specifies which references to read.

When to use each folder:

• workflows/ - Multi-step procedures Claude follows
• references/ - Domain knowledge Claude reads for context
• templates/ - Consistent output structures Claude copies and fills (plans, specs, configs)
• scripts/ - Executable code Claude runs as-is (deploy, setup, API calls)

4. Pure XML Structure

No markdown headings (#, ##, ###) in skill body. Use semantic XML tags:

<objective>...</objective>
<process>...</process>
<success_criteria>...</success_criteria>

Keep markdown formatting within content (bold, lists, code blocks).

5. Progressive Disclosure

SKILL.md under 500 lines. Split detailed content into reference files. Load only what's needed for the current workflow. </essential_principles>

Based on the user's message, route directly to the appropriate workflow:

Creating new skills:

• Domain expertise (exhaustive knowledge base) → Use create-domain-expertise skill instead (separate skill with batched subagent orchestration)
• Task-execution skill (does specific things) → workflows/create-new-skill.md

Working with existing skills:

• Audit, review, check → workflows/audit-skill.md
• Verify content is current → workflows/verify-skill.md
• Add workflow → workflows/add-workflow.md
• Add reference → workflows/add-reference.md
• Add template → workflows/add-template.md
• Add script → workflows/add-script.md
• Upgrade to router pattern → workflows/upgrade-to-router.md

Need help deciding:

• General guidance → workflows/get-guidance.md

If user intent is unclear, ask minimal clarifying questions:

• "Create a MIDI skill" → "Task-execution skill (does MIDI tasks) or domain expertise (complete MIDI knowledge base)?"
• "Work on my skill" → "Which skill? What do you want to do with it?"

Then proceed directly to the workflow.

<quick_reference>

Skill Structure Quick Reference

Skill directories:

• Global: ~/.gsd/agent/skills/{skill-name}/
• Project-local: .pi/agent/skills/{skill-name}/

Simple skill (single file):

---
name: skill-name
description: What it does and when to use it.
---

<objective>What this skill does</objective>
<quick_start>Immediate actionable guidance</quick_start>
<process>Step-by-step procedure</process>
<success_criteria>How to know it worked</success_criteria>

Complex skill (router pattern):

SKILL.md:
  <essential_principles> - Always applies
  <intake> - Question to ask
  <routing> - Maps answers to workflows

workflows/:
  <required_reading> - Which refs to load
  <process> - Steps
  <success_criteria> - Done when...

references/:
  Domain knowledge, patterns, examples

templates/:
  Output structures Claude copies and fills
  (plans, specs, configs, documents)

scripts/:
  Executable code Claude runs as-is
  (deploy, setup, API calls, data processing)

</quick_reference>

<reference_index>

Domain Knowledge

All in references/:

Structure: recommended-structure.md, skill-structure.md Principles: core-principles.md, be-clear-and-direct.md, use-xml-tags.md Patterns: common-patterns.md, workflows-and-validation.md Assets: using-templates.md, using-scripts.md Advanced: executable-code.md, api-security.md, iteration-and-testing.md GSD-specific: gsd-skill-ecosystem.md </reference_index>

<workflows_index>

Workflows

All in workflows/:

Workflow	Purpose
create-new-skill.md	Build a task-execution skill from scratch
audit-skill.md	Analyze skill against best practices
verify-skill.md	Check if content is still accurate
add-workflow.md	Add a workflow to existing skill
add-reference.md	Add a reference to existing skill
add-template.md	Add a template to existing skill
add-script.md	Add a script to existing skill
upgrade-to-router.md	Convert simple skill to router pattern
get-guidance.md	Help decide what kind of skill to build
</workflows_index>

<yaml_requirements>

YAML Frontmatter

Required fields:

---
name: skill-name          # lowercase-with-hyphens, matches directory
description: ...          # What it does AND when to use it (third person)
---

Name conventions: create-*, manage-*, setup-*, generate-*, build-* </yaml_requirements>

<success_criteria> A well-structured skill:

• Has valid YAML frontmatter
• Uses pure XML structure (no markdown headings in body)
• Has essential principles inline in SKILL.md
• Routes directly to appropriate workflows based on user intent
• Keeps SKILL.md under 500 lines
• Asks minimal clarifying questions only when truly needed
• Has been tested with real usage </success_criteria>