Skill Creator

Skill Creator

This skill provides guidance for creating effective skills.

About Skills

Skills are modular, self-contained packages that extend Claude's capabilities by providing specialized knowledge, workflows, and tools. Think of them as "onboarding guides" for specific domains or tasks—they transform Claude from a general-purpose agent into a specialized agent equipped with procedural knowledge that no model can fully possess.

What Skills Provide

1. Specialized workflows — Multi-step procedures for specific domains
2. Tool integrations — Instructions for working with specific file formats or APIs
3. Domain expertise — Company-specific knowledge, schemas, business logic
4. Bundled resources — Scripts, references, and assets for complex and repetitive tasks

Core Principles

Concise is Key

The context window is a public good. Skills share the context window with everything else Claude needs: system prompt, conversation history, other Skills' metadata, and the actual user request.

Default assumption: Claude is already very smart. Only add context Claude doesn't already have. Challenge each piece of information: "Does Claude really need this explanation?" and "Does this paragraph justify its token cost?"

Prefer concise examples over verbose explanations.

Set Appropriate Degrees of Freedom

Match the level of specificity to the task's fragility and variability:

High freedom (text-based instructions): Use when multiple approaches are valid, decisions depend on context, or heuristics guide the approach.

Medium freedom (pseudocode or scripts with parameters): Use when a preferred pattern exists, some variation is acceptable, or configuration affects behavior.

Low freedom (specific scripts, few parameters): Use when operations are fragile and error-prone, consistency is critical, or a specific sequence must be followed.

Think of Claude as exploring a path: a narrow bridge with cliffs needs specific guardrails (low freedom), while an open field allows many routes (high freedom).

Anatomy of a Skill

Every skill consists of a required SKILL.md file and optional bundled resources:

skill-name/
├── SKILL.md (required)
│   ├── YAML frontmatter: name (required), description (required)
│   └── Markdown instructions
└── Bundled Resources (optional)
    ├── scripts/     - Executable code (Python/Bash/etc.)
    ├── references/  - Documentation loaded into context as needed
    └── assets/      - Files used in output (templates, icons, etc.)

SKILL.md Frontmatter

• name: Unique identifier (lowercase, hyphens for spaces)
• description: What the skill does AND when to use it — this is the primary trigger

Body

• Keep under 500 lines
• Use imperative/infinitive form
• Move detailed content to references/ files and link from SKILL.md

Do NOT include: README.md, CHANGELOG.md, or other auxiliary documentation. Skills are for AI agents, not users.

Progressive Disclosure

Three-level loading system:

1. Metadata (name + description) — always in context (~100 words)
2. SKILL.md body — loaded when skill triggers (<5k words)
3. Bundled resources — loaded by Claude as needed

Keep SKILL.md under 500 lines. When splitting content to references, clearly describe when to read them.

Key principle: Keep core workflow in SKILL.md; move variant-specific details to reference files.

Example structure for multi-domain skills:

bigquery-skill/
├── SKILL.md (overview + navigation)
└── references/
    ├── finance.md
    ├── sales.md
    └── product.md

Claude only loads the relevant reference file when needed.

Creating a Skill

1. Understand concrete examples

Ask: "What would a user say to trigger this skill?" Collect 3-5 real examples.

2. Plan reusable contents

For each example, identify what scripts, references, or assets would avoid repeated work.

3. Create SKILL.md

---
name: my-skill
description: Brief description of what it does and when to use it.
---

# My Skill

[Core instructions here — only what Claude needs and doesn't already know]

## Quick Start
[Most common usage]

## Guidelines
[Key rules and constraints]

Writing Guidelines: Always use imperative/infinitive form.

Frontmatter

Write the YAML frontmatter with name and description:

• name: The skill name
• description: Primary trigger mechanism. Must include what the skill does AND when to use it (body only loads after triggering).
  • Example: "Document creation and editing with tracked changes. Use for: creating .docx files, modifying content, working with tracked changes."

Body

Write instructions for using the skill and its bundled resources. Keep it concise and focused on what Claude needs to know.

4. Add bundled resources (optional)

• scripts/ — deterministic code to avoid rewriting
• references/ — detailed docs, schemas, API specs
• assets/ — templates, fonts, boilerplate files

Avoid duplication: Information lives in SKILL.md OR references, not both.

5. Iterate

Test on real tasks. Improve based on actual performance gaps.

Iteration workflow:

1. Use the skill on real tasks
2. Notice struggles or inefficiencies
3. Identify how SKILL.md or bundled resources should be updated
4. Implement changes and test again

What NOT to Include

• README.md, INSTALLATION.md, CHANGELOG.md
• Explanations of things Claude already knows
• Verbose examples when concise ones suffice