skill-creator by fredrikaverpil

---
name: skill-creator
description: Guide for creating effective skills. This skill should be used when users want to create a new skill (or update an existing skill) that extends Claude's capabilities with specialized knowledge, workflows, or tool integrations.
---

# 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

### Anatomy of a Skill

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

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

#### Requirements (important)

- Skill should be combined into specific topics, for example: `cloudflare`,
  `cloudflare-r2`, `cloudflare-workers`, `docker`, `gcloud` should be combined
  into `devops`
- `SKILL.md` should be **less than 200 lines** and include the references of
  related markdown files and scripts.
- Each script or referenced markdown file should be also **less than 200
  lines**, remember that you can always split them into multiple files
  (**progressive disclosure** principle).
- Descriptions in metadata of `SKILL.md` files should be both concise and still
  contains enough usecases of the references and scripts, this will help skills
  can be activated automatically during the implementation process of Claude
  Code.
- **Referenced markdowns**:
  - Sacrifice grammar for the sake of concision when writing these files.
  - Can reference other markdown files or scripts as well.
- **Referenced scripts**:
  - Prefer nodejs or python scripts instead of bash script, because bash scripts
    are not well-supported on Windows.
  - If you're going to write python scripts, make sure you have
    `requirements.txt`
  - Make sure scripts respect `.env` file follow this order: `process.env` >
    `.claude/skills/${SKILL}/.env` > `.claude/skills/.env` > `.claude/.env`
  - Create `.env.example` file to show the required environment variables.
  - Always write tests for these scripts.

**Why?** Better **context engineering**: inspired from **progressive
disclosure** technique of Agent Skills, when agent skills are activated, Claude
Code will consider to load only relevant files into the context, instead of
reading all long `SKILL.md` as before.

#### SKILL.md (required)

**File name:** `SKILL.md` (uppercase) **File size:** Under 200 lines, if you
need more, plit it to multiple files in `references` folder.

**Metadata Quality:** The `name` and `description` in YAML frontmatter determine
when Claude will use the skill. Be specific about what the skill does and when
to use it. Use the third-person (e.g. "This skill should be used when..."
instead of "Use this skill when...").

#### Bundled Resources (optional)

##### Scripts (`scripts/`)

Executable code (Python/Bash/etc.) for tasks that require deterministic
reliability or are repeatedly rewritten.

- **When to include**: When the same code is being rewritten repeatedly or
  deterministic reliability is needed
- **Example**: `scripts/rotate_pdf.py` for PDF rotation tasks
- **Benefits**: Token efficient, deterministic, may be executed without loading
  into context
- **Note**: Scripts may still need to be read by Claude for patching or
  environment-specific adjustments

##### References (`references/`)

Documentation and reference material intended to be loaded as needed into
context to inform Claude's process and thinking.

- **When to include**: For documentation that Claude should reference while
  working
- **Examples**: `references/finance.md` for financial schemas,
  `references/mnda.md` for company NDA template, `references/policies.md` for
  company policies, `references/api_docs.md` for API specifications
- **Use cases**: Database schemas, API documentation, domain knowledge, company
  policies, detailed workflow guides
- **Benefits**: Keeps SKILL.md lean, loaded only when Claude determines it's
  needed
- **Best practice**: If files are large (>10k words), include grep search
  patterns in SKILL.md
- **Avoid duplication**: Information should live in either SKILL.md or
  references files, not both. Prefer references files for detailed information
  unless it's truly core to the skill—this keeps SKILL.md lean while making
  information discoverable without hogging the context window. Keep only
  essential procedural instructions and workflow guidance in SKILL.md; move
  detailed reference material, schemas, and examples to references files.

##### Assets (`assets/`)

Files not intended to be loaded into context, but rather used within the output
Claude produces.

- **When to include**: When the skill needs files that will be used in the final
  output
- **Examples**: `assets/logo.png` for brand assets, `assets/slides.pptx` for
  PowerPoint templates, `assets/frontend-template/` for HTML/React boilerplate,
  `assets/font.ttf` for typography
- **Use cases**: Templates, images, icons, boilerplate code, fonts, sample
  documents that get copied or modified
- **Benefits**: Separates output resources from documentation, enables Claude to
  use files without loading them into context

### Progressive Disclosure Design Principle

Skills use a three-level loading system to manage context efficiently:

1. **Metadata (name + description)** - Always in context (~100 words)
2. **SKILL.md body** - When skill triggers (<5k words)
3. **Bundled resources** - As needed by Claude (Unlimited\*)

\*Unlimited because scripts can be executed without reading into context window.

## Skill Creation Process

To create a skill, follow the "Skill Creation Process" in order, skipping steps
only if there is a clear reason why they are not applicable.

### Step 1: Understanding the Skill with Concrete Examples

Skip this step only when the skill's usage patterns are already clearly
understood. It remains valuable even when working with an existing skill.

To create an effective skill, clearly understand concrete examples of how the
skill will be used. This understanding can come from either direct user examples
or generated examples that are validated with user feedback.

For example, when building an image-editor skill, relevant questions include:

- "What functionality should the image-editor skill support? Editing, rotating,
  anything else?"
- "Can you give some examples of how this skill would be used?"
- "I can imagine users asking for things like 'Remove the red-eye from this
  image' or 'Rotate this image'. Are there other ways you imagine this skill
  being used?"
- "What would a user say that should trigger this skill?"

To avoid overwhelming users, avoid asking too many questions in a single
message. Start with the most important questions and follow up as needed for
better effectiveness.

Conclude this step when there is a clear sense of the functionality the skill
should support.

### Step 2: Planning the Reusable Skill Contents

To turn concrete examples into an effective skill, analyze each example by:

1. Considering how to execute on the example from scratch
2. Identifying what scripts, references, and assets would be helpful when
   executing these workflows repeatedly

Example: When building a `pdf-editor` skill to handle queries like "Help me
rotate this PDF," the analysis shows:

1. Rotating a PDF requires re-writing the same code each time
2. A `scripts/rotate_pdf.py` script would be helpful to store in the skill

Example: When designing a `frontend-webapp-builder` skill for queries like
"Build me a todo app" or "Build me a dashboard to track my steps," the analysis
shows:

1. Writing a frontend webapp requires the same boilerplate HTML/React each time
2. An `assets/hello-world/` template containing the boilerplate HTML/React
   project files would be helpful to store in the skill

Example: When building a `big-query` skill to handle queries like "How many
users have logged in today?" the analysis shows:

1. Querying BigQuery requires re-discovering the table schemas and relationships
   each time
2. A `references/schema.md` file documenting the table schemas would be helpful
   to store in the skill

To establish the skill's contents, analyze each concrete example to create a
list of the reusable resources to include: scripts, references, and assets.

### Step 3: Initializing the Skill

At this point, it is time to actually create the skill.

Skip this step only if the skill being developed already exists, and iteration
or packaging is needed. In this case, continue to the next step.

When creating a new skill from scratch, always run the `init_skill.py` script.
The script conveniently generates a new template skill directory that
automatically includes everything a skill requires, making the skill creation
process much more efficient and reliable.

Usage:

```bash
scripts/init_skill.py <skill-name> --path <output-directory>
```

The script:

- Creates the skill directory at the specified path
- Generates a SKILL.md template with proper frontmatter and TODO placeholders
- Creates example resource directories: `scripts/`, `references/`, and `assets/`
- Adds example files in each directory that can be customized or deleted

After initialization, customize or remove the generated SKILL.md and example
files as needed.

### Step 4: Edit the Skill

When editing the (newly-generated or existing) skill, remember that the skill is
being created for another instance of Claude to use. Focus on including
information that would be beneficial and non-obvious to Claude. Consider what
procedural knowledge, domain-specific details, or reusable assets would help
another Claude instance execute these tasks more effectively.

#### Start with Reusable Skill Contents

To begin implementation, start with the reusable resources identified above:
`scripts/`, `references/`, and `assets/` files. Note that this step may require
user input. For example, when implementing a `brand-guidelines` skill, the user
may need to provide brand assets or templates to store in `assets/`, or
documentation to store in `references/`.

Also, delete any example files and directories not needed for the skill. The
initialization script creates example files in `scripts/`, `references/`, and
`assets/` to demonstrate structure, but most skills won't need all of them.

#### Update SKILL.md

**Writing Style:** Write the entire skill using **imperative/infinitive form**
(verb-first instructions), not second person. Use objective, instructional
language (e.g., "To accomplish X, do Y" rather than "You should do X" or "If you
need to do X"). This maintains consistency and clarity for AI consumption.

To complete SKILL.md, answer the following questions:

1. What is the purpose of the skill, in a few sentences?
2. When should the skill be used?
3. In practice, how should Claude use the skill? All reusable skill contents
   developed above should be referenced so that Claude knows how to use them.

### Step 5: Packaging a Skill

Once the skill is ready, it should be packaged into a distributable zip file
that gets shared with the user. The packaging process automatically validates
the skill first to ensure it meets all requirements:

```bash
scripts/package_skill.py <path/to/skill-folder>
```

Optional output directory specification:

```bash
scripts/package_skill.py <path/to/skill-folder> ./dist
```

The packaging script will:

1. **Validate** the skill automatically, checking:
   - YAML frontmatter format and required fields
   - Skill naming conventions and directory structure
   - Description completeness and quality
   - File organization and resource references

2. **Package** the skill if validation passes, creating a zip file named after
   the skill (e.g., `my-skill.zip`) that includes all files and maintains the
   proper directory structure for distribution.

If validation fails, the script will report the errors and exit without creating
a package. Fix any validation errors and run the packaging command again.

### Step 6: Iterate

After testing the skill, users may request improvements. Often this happens
right after using the skill, with fresh context of how the skill performed.

**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

## References

- [Agent Skills](https://docs.claude.com/en/docs/claude-code/skills.md)
- [Agent Skills Spec](.claude/skills/agent_skills_spec.md)
- [Agent Skills Overview](https://docs.claude.com/en/docs/agents-and-tools/agent-skills/overview.md)
- [Best Practices](https://docs.claude.com/en/docs/agents-and-tools/agent-skills/best-practices.md)