Skill Creator+

Guide for creating and reviewing effective skills.

When to Use

• Create skill, new skill, review skill, スキル作成
• Creating a new skill from scratch
• Updating or refactoring an existing skill
• Reviewing existing SKILL.md files → See references/skill-review-checklist.md

Core Principles

Principle	Description
Concise is Key	Context window is shared. Only add what Claude doesn't already know.
Degrees of Freedom	Match specificity to task fragility (high/medium/low freedom)
Progressive Disclosure	Split into 3 levels: Metadata → Body → References

Default assumption: Claude is already very smart. Challenge each piece: "Does this justify its token cost?"

Skill Structure

→ references/skill-structure.md for details

skill-name/
├── SKILL.md (required)        # < 150 lines
├── scripts/                   # Executable code
├── references/                # Documentation loaded on demand
└── assets/                    # Output resources (templates, images)

→ See skill-structure.md > What NOT to Include for excluded files.

Creation Process

→ references/creation-process.md for details

Step	Action
1	Understand with concrete examples
2	Plan reusable contents (scripts/references/assets)
3	Initialize: scripts/init_skill.py <name> --path <dir>
4	Edit skill and implement resources
5	Package: scripts/package_skill.py <path>
6	Iterate based on real usage

SKILL.md Guidelines

Size Target

→ See skill-review-checklist.md > Line Count Target for size guidelines.

Quick rule: < 150 lines is good, > 300 lines must split to references.

Frontmatter

---
name: skill-name
description: "What it does. Use when [trigger conditions]. Triggers on 'keyword', 'phrase'."
---

Description must include: What the skill does AND when to trigger it.

⚠️ Why this matters: Skills may not be invoked if descriptions lack clear triggers. Include user phrases to improve routing accuracy.

✅ Good	❌ Bad
Extract text and tables from PDF files, fill forms, merge documents. Use when working with PDF files or when the user mentions PDFs, forms, or document extraction.	Helps with documents
Set up book writing workspace. Triggers on "book writing", "執筆ワークスペース", "technical writing project".	Creates workspaces

When to Use Section

Start with generic keywords users are likely to say:

## When to Use

- **PDF**, **extract text**, **form filling** ← Keywords first
- Processing documents with embedded images
- Filling PDF forms programmatically

Body

• Use imperative/infinitive form
• Link to references for details
• Keep essential workflow only

Review Checklist

→ references/skill-review-checklist.md

- [ ] SKILL.md under 150 lines?
- [ ] Description has trigger conditions?
- [ ] Details moved to references/?
- [ ] No README.md or auxiliary docs?

Key References

Topic	Reference
Skill Structure	references/skill-structure.md
Creation Process	references/creation-process.md
Review Checklist	references/skill-review-checklist.md
Workflows	references/workflows.md
Output Patterns	references/output-patterns.md

Done Criteria

• SKILL.md created and under 150 lines
• Frontmatter has name + description with trigger conditions
• Details moved to references/ (Progressive Disclosure)
• Review checklist passed