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