Guide users through creating Agent Skills for Claude Code. Use when the user wants to create, write, author, or design a new Skill, or needs help with SKILL.md files, frontmatter, or skill structure.
The description is critical for Claude to discover your Skill.
Formula: [What it does] + [When to use it] + [Key triggers]
Examples:
β Good:
description: 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.
β Good:
description: Analyze Excel spreadsheets, create pivot tables, and generate charts. Use when working with Excel files, spreadsheets, or analyzing tabular data in .xlsx format.
β Too vague:
description: Helps with documents
description: For data analysis
Tips:
Include specific file extensions (.pdf, .xlsx, .json)
Mention common user phrases ("analyze", "extract", "generate")
List concrete operations (not generic verbs)
Add context clues ("Use when...", "For...")
Step 6: Structure the Skill content
Use clear Markdown sections:
# Skill Name
Brief overview of what this Skill does.
## Quick start
Provide a simple example to get started immediately.
## Instructions
Step-by-step guidance for Claude:
1. First step with clear action
2. Second step with expected outcome
3. Handle edge cases
## Examples
Show concrete usage examples with code or commands.
## Best practices
- Key conventions to follow
- Common pitfalls to avoid
- When to use vs. not use
## Requirements
List any dependencies or prerequisites:
```bash
pip install package-name
### Step 7: Add supporting files (optional)
Create additional files for progressive disclosure:
**reference.md**: Detailed API docs, advanced options
**examples.md**: Extended examples and use cases
**scripts/**: Helper scripts and utilities
**templates/**: File templates or boilerplate
Reference them from SKILL.md:
```markdown
For advanced usage, see [reference.md](reference.md).
Run the helper script:
\`\`\`bash
python scripts/helper.py input.txt
\`\`\`
Step 8: Validate the Skill
Check these requirements:
β File structure:
SKILL.md exists in correct location
Directory name matches frontmatter name
β YAML frontmatter:
Opening --- on line 1
Closing --- before content
Valid YAML (no tabs, correct indentation)
name follows naming rules
description is specific and < 1024 chars
β Content quality:
Clear instructions for Claude
Concrete examples provided
Edge cases handled
Dependencies listed (if any)
β Testing:
Description matches user questions
Skill activates on relevant queries
Instructions are clear and actionable
Step 9: Test the Skill
Restart Claude Code (if running) to load the Skill
Ask relevant questions that match the description:
Can you help me extract text from this PDF?
Verify activation: Claude should use the Skill automatically
Check behavior: Confirm Claude follows the instructions correctly
Step 10: Debug if needed
If Claude doesn't use the Skill:
Make description more specific:
Add trigger words
Include file types
Mention common user phrases
Check file location:
ls ~/.claude/skills/skill-name/SKILL.md
ls .claude/skills/skill-name/SKILL.md
Validate YAML:
cat SKILL.md | head -n 10
Run debug mode:
claude --debug
Common patterns
Read-only Skill
---
name: code-reader
description: Read and analyze code without making changes. Use for code review, understanding codebases, or documentation.
allowed-tools: Read, Grep, Glob
---
Script-based Skill
---
name: data-processor
description: Process CSV and JSON data files with Python scripts. Use when analyzing data files or transforming datasets.
---
# Data Processor
## Instructions
1. Use the processing script:
\`\`\`bash
python scripts/process.py input.csv --output results.json
\`\`\`
2. Validate output with:
\`\`\`bash
python scripts/validate.py results.json
\`\`\`
Multi-file Skill with progressive disclosure
---
name: api-designer
description: Design REST APIs following best practices. Use when creating API endpoints, designing routes, or planning API architecture.
---
# API Designer
Quick start: See [examples.md](examples.md)
Detailed reference: See [reference.md](reference.md)
## Instructions
1. Gather requirements
2. Design endpoints (see examples.md)
3. Document with OpenAPI spec
4. Review against best practices (see reference.md)
Best practices for Skill authors
One Skill, one purpose: Don't create mega-Skills
Specific descriptions: Include trigger words users will say
Clear instructions: Write for Claude, not humans
Concrete examples: Show real code, not pseudocode
List dependencies: Mention required packages in description
Test with teammates: Verify activation and clarity
Version your Skills: Document changes in content
Use progressive disclosure: Put advanced details in separate files
Validation checklist
Before finalizing a Skill, verify:
Name is lowercase, hyphens only, max 64 chars
Description is specific and < 1024 chars
Description includes "what" and "when"
YAML frontmatter is valid
Instructions are step-by-step
Examples are concrete and realistic
Dependencies are documented
File paths use forward slashes
Skill activates on relevant queries
Claude follows instructions correctly
Troubleshooting
Skill doesn't activate:
Make description more specific with trigger words
Include file types and operations in description
Add "Use when..." clause with user phrases
Multiple Skills conflict:
Make descriptions more distinct
Use different trigger words
Narrow the scope of each Skill
Skill has errors:
Check YAML syntax (no tabs, proper indentation)
Verify file paths (use forward slashes)
Ensure scripts have execute permissions
List all dependencies
Examples
See the documentation for complete examples:
Simple single-file Skill (commit-helper)
Skill with tool permissions (code-reviewer)
Multi-file Skill (pdf-processing)
Output format
When creating a Skill, I will:
Ask clarifying questions about scope and requirements
Suggest a Skill name and location
Create the SKILL.md file with proper frontmatter
Include clear instructions and examples
Add supporting files if needed
Provide testing instructions
Validate against all requirements
The result will be a complete, working Skill that follows all best practices and validation rules.