skill-creator skill

---
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.
argument-hint: "[skill-name]"
license: Complete terms in LICENSE.txt
---

# Skill Creator

This skill provides guidance for creating effective skills.

## 1. 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.

### 1.1. 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

## 2. Core Principles

### 2.1. 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.

### 2.2. 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).

### 2.3. Anatomy of a Skill

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

```text
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 loaded into context as needed
    └── assets/      - Files used in output (templates, icons, fonts)
```

#### 2.3.1. SKILL.md (required)

Every SKILL.md consists of:

- **Frontmatter** (YAML): Contains `name` and `description` fields.
  These are the only fields that Claude reads to determine when the
  skill gets used, thus it is very important to be clear and
  comprehensive in describing what the skill is, and when it should
  be used.
- **Body** (Markdown): Instructions and guidance for using the skill.
  Only loaded AFTER the skill triggers (if at all).

#### 2.3.2. Bundled Resources (optional)

##### 2.3.2.1. 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

##### 2.3.2.2. 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.

##### 2.3.2.3. 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

#### 2.3.3. What to Not Include in a Skill

A skill should only contain essential files that directly support its
functionality. Do NOT create extraneous documentation or auxiliary
files, including:

- README.md
- INSTALLATION_GUIDE.md
- QUICK_REFERENCE.md
- CHANGELOG.md
- etc.

The skill should only contain the information needed for an AI agent
to do the job at hand. It should not contain auxiliary context about
the process that went into creating it, setup and testing procedures,
user-facing documentation, etc. Creating additional documentation files
just adds clutter and confusion.

### 2.4. 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 because
   scripts can be executed without reading into context window)

#### 2.4.1. Progressive Disclosure Patterns

Keep SKILL.md body to the essentials and under 500 lines to minimize
context bloat. Split content into separate files when approaching this
limit. When splitting out content into other files, it is very
important to reference them from SKILL.md and describe clearly when
to read them, to ensure the reader of the skill knows they exist and
when to use them.

**Key principle:** When a skill supports multiple variations,
frameworks, or options, keep only the core workflow and selection
guidance in SKILL.md. Move variant-specific details (patterns,
examples, configuration) into separate reference files.

#### Pattern 1: High-level guide with references

```markdown
# PDF Processing

## Quick start

Extract text with pdfplumber:
[code example]

## Advanced features

- **Form filling**: See [FORMS.md](FORMS.md) for complete guide
- **API reference**: See [REFERENCE.md](REFERENCE.md) for all methods
- **Examples**: See [EXAMPLES.md](EXAMPLES.md) for common patterns
```

Claude loads FORMS.md, REFERENCE.md, or EXAMPLES.md only when needed.

#### Pattern 2: Domain-specific organization

For Skills with multiple domains, organize content by domain to avoid
loading irrelevant context:

```text
bigquery-skill/
├── SKILL.md (overview and navigation)
└── reference/
    ├── finance.md (revenue, billing metrics)
    ├── sales.md (opportunities, pipeline)
    ├── product.md (API usage, features)
    └── marketing.md (campaigns, attribution)
```

When a user asks about sales metrics, Claude only reads sales.md.

Similarly, for skills supporting multiple frameworks or variants,
organize by variant:

```text
cloud-deploy/
├── SKILL.md (workflow + provider selection)
└── references/
    ├── aws.md (AWS deployment patterns)
    ├── gcp.md (GCP deployment patterns)
    └── azure.md (Azure deployment patterns)
```

When the user chooses AWS, Claude only reads aws.md.

#### Pattern 3: Conditional details

Show basic content, link to advanced content:

```markdown
# DOCX Processing

## Creating documents

Use docx-js for new documents. See [DOCX-JS.md](DOCX-JS.md).

## Editing documents

For simple edits, modify the XML directly.

**For tracked changes**: See [REDLINING.md](REDLINING.md)
**For OOXML details**: See [OOXML.md](OOXML.md)
```

Claude reads REDLINING.md or OOXML.md only when the user needs those
features.

**Important guidelines:**

- **Avoid deeply nested references** - Keep references one level deep
  from SKILL.md. All reference files should link directly from
  SKILL.md.
- **Structure longer reference files** - For files longer than 100
  lines, include a table of contents at the top so Claude can see
  the full scope when previewing.

## 3. Skill Creation Process

Skill creation involves these steps:

1. Understand the skill with concrete examples
2. Plan reusable skill contents (scripts, references, assets)
3. Initialize the skill (run init_skill.py)
4. Edit the skill (implement resources and write SKILL.md)
5. Package the skill (run package_skill.py)
6. Iterate based on real usage

Follow these steps in order, skipping only if there is a clear reason
why they are not applicable.

### 3.1. 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.

### 3.2. 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.

### 3.3. 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
python 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.

### 3.4. 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.
Include 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.

#### 3.4.1. Learn Proven Design Patterns

Consult these helpful guides based on your skill's needs:

- **Multi-step processes**: See references/workflows.md for sequential
  workflows and conditional logic
- **Specific output formats or quality standards**: See
  references/output-patterns.md for template and example patterns

These files contain established best practices for effective skill
design.

#### 3.4.2. 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/`.

Added scripts must be tested by actually running them to ensure there
are no bugs and that the output matches what is expected. If there are
many similar scripts, only a representative sample needs to be tested
to ensure confidence that they all work while balancing time to
completion.

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

#### 3.4.3. Update SKILL.md

**Writing Guidelines:** Always use imperative/infinitive form.

##### 3.4.3.1. Frontmatter

Write the YAML frontmatter with `name` and `description`:

- `name`: The skill name
- `description`: This is the primary triggering mechanism for your
  skill, and helps Claude understand when to use the skill.
    - Include both what the Skill does and specific triggers/contexts
      for when to use it.
    - Include all "when to use" information here - Not in the body.
      The body is only loaded after triggering, so "When to Use This
      Skill" sections in the body are not helpful to Claude.
    - Example description for a `docx` skill: "Comprehensive document
      creation, editing, and analysis with support for tracked changes,
      comments, formatting preservation, and text extraction. Use when
      Claude needs to work with professional documents (.docx files)
      for: (1) Creating new documents, (2) Modifying or editing
      content, (3) Working with tracked changes, (4) Adding comments,
      or any other document tasks"

Do not include any other fields in YAML frontmatter.

##### 3.4.3.2. Body

Write instructions for using the skill and its bundled resources.

### 3.5. Step 5: Packaging a Skill

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

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

Optional output directory specification:

```bash
python 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 .skill file
   named after the skill (e.g., `my-skill.skill`) that includes all
   files and maintains the proper directory structure for distribution.
   The .skill file is a zip file with a .skill extension.

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.

### 3.6. 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