skill-creator

Create a New Skill

Guide the user through creating a new agent skill following the Agent Skills specification. Follow each step in order.

Step 1: Understand the Skill

Gather requirements before writing anything.

Ask the user:

1. What should this skill do? (one sentence)
2. When should an agent use it? (trigger phrases)
3. What tools does the skill need? (Read, Grep, Glob, Bash, Task, WebFetch, etc.)
4. Where should the skill live? (which plugin or directory)

Determine the skill name:

• Lowercase alphanumeric with hyphens, 1-64 characters
• Descriptive and unique among existing skills
• Check the target skills directory to avoid name collisions

Choose a complexity tier:

Read ${CLAUDE_SKILL_ROOT}/references/design-principles.md for guidance on keeping skills focused and concise.

Step 2: Study Existing Skills

Before writing, study 1-2 existing skills that match the chosen tier. Look for skills in the target repository or plugin to understand local conventions.

Read ${CLAUDE_SKILL_ROOT}/references/skill-patterns.md for concrete examples of each tier.

Also read CLAUDE.md (or AGENTS.md) at the repository root for repo-specific conventions that the skill should follow.

Step 3: Write the SKILL.md

Create <skill-directory>/<name>/SKILL.md.

Frontmatter

The YAML frontmatter must be the first thing in the file. No comments or blank lines before ---.

---
name: <skill-name>
description: <what it does>. Use when <trigger phrases>. <key capabilities>.
---

Required fields:

• name — must match the directory name exactly
• description — up to 1024 chars; include trigger keywords that help agents match user intent

Optional fields:

• model — override model (sonnet, opus, haiku); omit to use the user's default
• allowed-tools — space-delimited list (e.g., Read Grep Glob Bash Task); omit to allow all tools
• license — license name or path (add when vendoring external content)

Body Guidelines

Write the body in imperative voice — these are instructions, not documentation.

Structure:

1. Start with a one-line summary of what the skill does
2. Organize steps with ## Step N: Title headings
3. Use tables for decision logic and mappings
4. Include concrete examples of expected output
5. End with validation criteria or exit conditions

Size limits:

• Keep SKILL.md under 500 lines
• If approaching the limit, move reference material to references/ files
• Load reference files conditionally based on context (not all at once)

Attribution

If the skill is based on or adapted from external sources, add an HTML comment after the frontmatter closing ---:

---
name: example
description: ...
---
 
<!--
Based on [Original Name] by [Author/Org]:
https://github.com/example/original-source

Step 4: Create Supporting Files

References (references/)

Use for domain knowledge the agent loads conditionally.

Reference from SKILL.md with:

Keep each reference file focused on one topic. Use markdown with tables and code blocks.

Scripts (scripts/)

Use for workflow automation that benefits from structured Python.

Script requirements:

• Always use uv run to execute: uv run ${CLAUDE_SKILL_ROOT}/scripts/do_thing.py
• Add PEP 723 inline metadata for dependencies:

• Output structured JSON for agent consumption
• Run from the repository root, not the skill directory
• Document the script's interface in SKILL.md (arguments, output format)

Assets (assets/)

Use for static files the skill references (templates, configs, etc.).

LICENSE

Include a LICENSE file in the skill directory when vendoring content with specific licensing requirements.

Step 5: Register the Skill

Registration steps vary by repository. Check the repository's CLAUDE.md or README.md for specific instructions.

1. Verify directory-name match — confirm the directory name matches the name field in SKILL.md frontmatter exactly
2. Update documentation — add the skill to any skills index or table in README.md
3. Update permissions — if the repo has .claude/settings.json, add Skill(<plugin>:<name>) to the permissions.allow array
4. Check CLAUDE.md — read the repository's CLAUDE.md for any additional registration steps specific to that project

Step 6: Verify

Run through this checklist before finishing:

Frontmatter

• name matches directory name
• description is under 1024 characters
• description includes trigger keywords
• No content before the opening ---

Content

• SKILL.md is under 500 lines
• Written in imperative voice
• Steps are numbered and clear
• Examples of expected output included
• Reference files loaded conditionally (not unconditionally)

Registration

• Directory name matches frontmatter name
• Skill added to repo documentation (README or equivalent)
• Permissions updated (if applicable)
• Any repo-specific registration steps completed (check CLAUDE.md)

Scripts (if applicable)

• Uses uv run ${CLAUDE_SKILL_ROOT}/scripts/...
• Has PEP 723 inline metadata
• Outputs structured JSON
• Documented in SKILL.md

Report any issues found and fix them before completing.