skill-creator

name: skill-creator version: 1.0.0 description: "This skill should be used when the user asks to 'create a skill', 'build a skill', 'make a skill', 'new skill', 'write a skill', 'skill for X', or wants to package a workflow as a reusable Claude Code skill. Guides through use case definition, frontmatter, instructions, testing, and file structure. NOT for reviewing existing skills — use /skill-content-reviewer instead."

Skill Creator

Interactive guide for creating well-structured Claude Code skills. Walks through use case definition, frontmatter generation, instruction writing, reference organization, and validation.

This is a DESIGN + BUILD skill — first plan the skill, then generate the files.

Based on The Complete Guide to Building Skills for Claude by Anthropic.

Workflow

Step 1: Define Use Cases

Before writing anything, identify 2-3 concrete use cases.

Ask the user:

1. What task should this skill automate or guide?
2. What would a user say to trigger it? (collect 3-5 trigger phrases)
3. Which category fits best?
   • Document/Asset Creation — consistent output generation
   • Workflow Automation — multi-step processes with validation gates
   • MCP Enhancement — workflow guidance on top of MCP tool access

Capture:

• Target outcome per use case
• Required tools (built-in, MCP, scripts)
• Domain knowledge to embed

Step 2: Plan Structure

Choose complexity level based on content size:

Plan the folder layout:

skill-name/
├── SKILL.md              # Required — main instructions
├── references/           # Optional — detailed docs
│   ├── topic-a.md
│   └── topic-b.md
├── scripts/              # Optional — executable code
├── assets/               # Optional — templates, icons
└── examples/             # Optional — example implementations

Step 3: Write Frontmatter

Generate YAML frontmatter following these rules:

Required fields:

• name: kebab-case, matches folder name, no spaces/capitals
• description: WHAT it does + WHEN to use it + trigger phrases. Max 1024 chars. No XML tags.

Optional fields:

• version: semver string
• license: MIT, Apache-2.0, etc.
• allowed-tools: space-separated tool list (e.g., "Bash(python:*) WebFetch Read")
• metadata: author, version, mcp-server, tags, etc.
• compatibility: environment requirements (1-500 chars)

Frontmatter template:

---
name: my-skill-name
description: "This skill should be used when the user asks to '[trigger phrase 1]', '[trigger phrase 2]', or [broader description]. [What it does in one sentence]."
---

Critical rules:

• File MUST be named SKILL.md (case-insensitive per spec, but uppercase recommended)
• Folder MUST be kebab-case
• No claude or anthropic in skill name (reserved)
• No XML angle brackets in frontmatter
• Description MUST include both WHAT and WHEN

See references/description-examples.md for good/bad examples.

Step 4: Write Instructions

Structure the SKILL.md body using this template:

# Skill Name

Brief overview — what problem this solves.

---

## When to Use This Skill

Bullet list of trigger conditions.

## Workflow / Instructions

### Step 1: [First Major Step]
Clear explanation with actionable details.

### Step 2: [Next Step]
Include validation/checks between steps.

## Examples

Example 1: [common scenario]
User says: "..."
Actions: ...
Result: ...

## Troubleshooting

Error: [Common error]
Cause: [Why]
Solution: [Fix]

## Constraints

- Hard rules the skill must follow

Instruction quality checklist:

• Specific and actionable (not "validate things properly")
• Critical instructions at the top
• Bullet points and numbered lists over prose
• Reference bundled resources explicitly (references/api-patterns.md)
• Include error handling for common failures
• Add examples with expected inputs/outputs
• Keep SKILL.md under 5,000 words — move detail to references/

Step 5: Write Reference Files (if needed)

For medium/heavy skills, create reference files:

• Each file focused on one sub-topic
• Track token costs in a reference table in SKILL.md:

| Section | File | ~Tokens |
|---------|------|---------|
| Topic A | `references/topic-a.md` | 2,500 |
| Topic B | `references/topic-b.md` | 4,500 |

Step 6: Validate

Run through this checklist before finalizing:

Structure:

• Folder is kebab-case
• SKILL.md exists (exact case)
• YAML frontmatter has --- delimiters
• name field is kebab-case, matches folder
• description includes WHAT + WHEN + trigger phrases
• No XML tags in frontmatter

Content:

• Instructions are specific and actionable
• Error handling included
• Examples provided
• References clearly linked
• SKILL.md under 5,000 words

Triggering (test mentally):

• Triggers on obvious task phrases
• Triggers on paraphrased requests
• Does NOT trigger on unrelated topics

Step 7: Place the Skill

Determine where the skill should live:

Prefer .github/skills/ for open-source or cross-platform projects (works with Copilot, Codex, etc.). Use .claude/skills/ for Claude-specific skills.

Patterns Reference

Five common skill patterns — choose based on use case:

1. Sequential Workflow — ordered steps with dependencies and validation gates
2. Multi-MCP Coordination — phases spanning multiple services with data passing
3. Iterative Refinement — draft → validate → improve loops with quality thresholds
4. Context-Aware Selection — decision trees choosing tools based on input
5. Domain Intelligence — embedded expertise (compliance, best practices, standards)

See references/patterns.md for detailed examples.

Troubleshooting

Skill not triggering:

• Description missing trigger phrases — add specific user utterances
• Description too vague — "helps with projects" won't match anything
• Wrong folder — verify skill is in a .claude/skills/ or .github/skills/ directory Claude discovers

Description validation error (>1024 chars):

• Move detail to SKILL.md body, keep description to WHAT + WHEN + triggers only
• Cut redundant trigger phrases — keep 3-5 most distinctive ones

Skill not discovered:

• Folder name doesn't match name field in frontmatter
• SKILL.md missing or wrong case
• Nested too deep — skills must be direct children of a skills/ directory

Skill loads but behaves wrong:

• Instructions too vague — use specific verbs, not "validate properly"
• Missing constraints — add hard rules for what the skill must/must not do
• References not linked — Claude won't read files it doesn't know about

Anti-Patterns

• Description too vague ("Helps with projects")
• Description missing trigger phrases
• Instructions too verbose — move detail to references
• All content inline instead of progressive disclosure
• Ambiguous language ("make sure to validate things properly")
• Missing error handling
• No examples

Constraints

• MUST ask user for use cases before generating any files
• MUST validate frontmatter against rules before writing
• MUST use kebab-case for folder and name
• MUST include trigger phrases in description
• MUST place critical instructions at top of SKILL.md
• If skill has hooks/agents, note integration points but don't generate those here — use separate tools

Step 8: Post-Creation Validation

After placing the skill, suggest running /skill-content-reviewer on it to validate structure, content quality, and triggering behavior.

Example: Complete Minimal Skill

my-formatter/
└── SKILL.md

---
name: my-formatter
version: 1.0.0
description: "This skill should be used when the user asks to 'format output', 'pretty print', 'clean up formatting', or needs consistent output formatting. Applies project formatting standards to generated content."
---

# My Formatter

Applies project-specific formatting standards to generated output.

## Workflow

### Step 1: Detect Content Type
Check if output is code, markdown, JSON, or prose.

### Step 2: Apply Rules
- Code: run project linter config
- Markdown: enforce heading hierarchy, link style
- JSON: 2-space indent, sorted keys
- Prose: sentence case headings, no trailing whitespace

### Step 3: Validate
Confirm formatting passes project checks. If not, re-apply.

## Constraints
- Never change content meaning — formatting only
- Preserve existing valid formatting choices