skill-creator git:20260321.8fae238A

Immutable. This exact content is served forever at /api/v1/blob/a7aeb08f5566a354.

---
name: skill-creator
description: Design a new Claude Code skill from a concrete use case and produce a repo-ready skill package. Use when the user asks to create a new skill, define a skill's responsibility, draft SKILL.md, choose frontmatter, design supporting files, or prepare eval criteria for a new skill. Also trigger on "スキルを作りたい", "スキルを作って", "スキルを追加して", "新しいスキル", "SKILL.md生成".
allowed-tools: Read, Grep, Glob, Bash, Write, Edit
---

## Purpose

Create a new skill only after the use case is concrete enough.

Your job is to:

1. identify the smallest useful responsibility
2. define when the skill should trigger
3. choose safe frontmatter defaults
4. draft a minimal but strong `SKILL.md`
5. propose supporting files only when they add clear value
6. define an initial eval set

## Safety constraints

Write output files only to `.claude/skills/` unless the user explicitly specifies a different path.
Do not modify existing skills without user confirmation.

Note: this skill does not set `disable-model-invocation: true` because file creation is its primary purpose, not an incidental side effect. The settings.json deny list and user confirmation prompts provide sufficient guardrails.

## Core rule

Do not create a broad or fuzzy skill.

Prefer:

- one responsibility
- one primary workflow
- one clear success condition

If the requested scope is too broad, split it into multiple skills.

## Phase 0: Gate

Before drafting, confirm:

- target outcome
- primary user intent
- trigger phrases
- audience
- allowed tools needed
- whether the skill should be auto-invoked or manual-only
- source material available
- definition of done

If any item is unclear:

- ask the minimum focused questions, or
- inspect available files first if the answer can be found without asking

Do not draft the full skill until the gate passes.

## Phase 1: Skill boundary design

Produce a short working summary with:

- skill name candidate
- single responsibility
- in-scope tasks
- out-of-scope tasks
- likely trigger language
- risk level

Reject designs that combine unrelated workflows.

## Phase 2: Frontmatter design

Choose frontmatter intentionally.

Defaults:

- include `name`
- include `description`
- omit extra fields unless clearly needed

Use:

- `disable-model-invocation: true` for side-effecting, sensitive, or timing-dependent workflows
- `allowed-tools` only when safe pre-approval is clearly useful
- `model` only when there is a concrete reason to override the default

For every chosen field, state why it is needed.

## Phase 3: Structure design

Draft the skill with this order:

1. purpose
2. gate
3. workflow phases
4. output contract
5. review step
6. failure handling
7. additional resources

Keep the main file compact.
Move heavy references, examples, and templates into separate files.

Use `${CLAUDE_SKILL_ROOT}/assets/basic-skill-template.md` as the starting skeleton.

## Phase 4: Eval design

Create an initial eval plan with:

- 10 to 20 realistic test prompts
- 3 to 6 pass/fail criteria
- likely failure modes
- what should be checked by code vs by reviewer

Include at least:

- one trigger test
- one under-specified request
- one boundary case
- one anti-pattern case

Use `${CLAUDE_SKILL_ROOT}/assets/eval-rubric-template.md` as the rubric structure.

## Phase 5: Review

Check the draft against:

- `${CLAUDE_SKILL_ROOT}/references/review-default.md`
- `${CLAUDE_SKILL_ROOT}/references/design-principles.md`

Fix any issue before finalizing.

## Phase 6: Registration

After the skill files are written:

1. verify the directory name matches the `name` field in frontmatter
2. verify `description` is under 1024 characters and includes trigger keywords
3. verify SKILL.md is under 500 lines
4. verify all `${CLAUDE_SKILL_ROOT}/` references point to existing files
5. check the repository CLAUDE.md or AGENTS.md for additional registration steps
6. if the repository uses a skills index or registry, update it

## Output format

Return exactly these sections:

### Skill summary

### Recommended directory structure

### SKILL.md draft

### Supporting files to add

### Eval plan

### Known risks

## Anti-patterns

Do not:

- create a "do everything" skill
- invent company-specific rules
- write a vague description
- skip the gate
- omit eval planning
- hide trade-offs

## Failure handling

If the request is too broad:

- propose 2 to 4 smaller skills
- explain the split by responsibility
- recommend which one to build first