Command Development Skill

Comprehensive guidance on creating Claude Code slash commands, including file format, frontmatter options, dynamic arguments, and best practices.

Overview

This skill provides knowledge about:

• Slash command file format and structure
• YAML frontmatter configuration fields
• Dynamic arguments ($ARGUMENTS, $1, $2, etc.)
• File references with @ syntax
• Bash execution with !` syntax
• Command organization and namespacing
• Best practices for command development
• Plugin-specific features (${CLAUDE_PLUGIN_ROOT}, plugin patterns)
• Integration with plugin components (agents, skills, hooks)
• Validation patterns and error handling

Skill Structure

SKILL.md (~2,470 words)

Core skill content covering:

Fundamentals:

• Command basics and locations
• File format (Markdown with optional frontmatter)
• YAML frontmatter fields overview
• Dynamic arguments ($ARGUMENTS and positional)
• File references (@ syntax)
• Bash execution (!` syntax)
• Command organization patterns
• Best practices and common patterns
• Troubleshooting

Plugin-Specific:

• ${CLAUDE_PLUGIN_ROOT} environment variable
• Plugin command discovery and organization
• Plugin command patterns (configuration, template, multi-script)
• Integration with plugin components (agents, skills, hooks)
• Validation patterns (argument, file, resource, error handling)

References

Detailed documentation:

• frontmatter-reference.md: Complete YAML frontmatter field specifications

  • All field descriptions with types and defaults
  • When to use each field
  • Examples and best practices
  • Validation and common errors

• plugin-features-reference.md: Plugin-specific command features

  • Plugin command discovery and organization
  • ${CLAUDE_PLUGIN_ROOT} environment variable usage
  • Plugin command patterns (configuration, template, multi-script)
  • Integration with plugin agents, skills, and hooks
  • Validation patterns and error handling

Examples

Practical command examples:

• simple-commands.md: 10 complete command examples

  • Code review commands
  • Testing commands
  • Deployment commands
  • Documentation generators
  • Git integration commands
  • Analysis and research commands

• plugin-commands.md: 10 plugin-specific command examples

  • Simple plugin commands with scripts
  • Multi-script workflows
  • Template-based generation
  • Configuration-driven deployment
  • Agent and skill integration
  • Multi-component workflows
  • Validated input commands
  • Environment-aware commands

When This Skill Triggers

Claude Code activates this skill when users:

• Ask to "create a slash command" or "add a command"
• Need to "write a custom command"
• Want to "define command arguments"
• Ask about "command frontmatter" or YAML configuration
• Need to "organize commands" or use namespacing
• Want to create commands with file references
• Ask about "bash execution in commands"
• Need command development best practices

Progressive Disclosure

The skill uses progressive disclosure:

1. SKILL.md (~2,470 words): Core concepts, common patterns, and plugin features overview
2. References (~13,500 words total): Detailed specifications
   • frontmatter-reference.md (~1,200 words)
   • plugin-features-reference.md (~1,800 words)
   • interactive-commands.md (~2,500 words)
   • advanced-workflows.md (~1,700 words)
   • testing-strategies.md (~2,200 words)
   • documentation-patterns.md (~2,000 words)
   • marketplace-considerations.md (~2,200 words)
3. Examples (~6,000 words total): Complete working command examples
   • simple-commands.md
   • plugin-commands.md

Claude loads references and examples as needed based on task.

Command Basics Quick Reference

File Format

---
description: Brief description
argument-hint: [arg1] [arg2]
allowed-tools: Read, Bash(git:*)
---

Command prompt content with:
- Arguments: $1, $2, or $ARGUMENTS
- Files: @path/to/file
- Bash: !`command here`

Locations

• Project: .claude/commands/ (shared with team)
• Personal: ~/.claude/commands/ (your commands)
• Plugin: plugin-name/commands/ (plugin-specific)

Key Features

Dynamic arguments:

• $ARGUMENTS - All arguments as single string
• $1, $2, $3 - Positional arguments

File references:

• @path/to/file - Include file contents

Bash execution:

• !command`` - Execute and include output

Frontmatter Fields Quick Reference

Common Patterns

Simple Review Command

---
description: Review code for issues
---

Review this code for quality and potential bugs.

Command with Arguments

---
description: Deploy to environment
argument-hint: [environment] [version]
---

Deploy to $1 environment using version $2

Command with File Reference

---
description: Document file
argument-hint: [file-path]
---

Generate documentation for @$1

Command with Bash Execution

---
description: Show Git status
allowed-tools: Bash(git:*)
---

Current status: !`git status`
Recent commits: !`git log --oneline -5`

Development Workflow

1. Design command:

   • Define purpose and scope
   • Determine required arguments
   • Identify needed tools

2. Create file:

   • Choose appropriate location
   • Create .md file with command name
   • Write basic prompt

3. Add frontmatter:

   • Start minimal (just description)
   • Add fields as needed (allowed-tools, etc.)
   • Document arguments with argument-hint

4. Test command:

   • Invoke with /command-name
   • Verify arguments work
   • Check bash execution
   • Test file references

5. Refine:

   • Improve prompt clarity
   • Handle edge cases
   • Add examples in comments
   • Document requirements

Best Practices Summary

1. Single responsibility: One command, one clear purpose
2. Clear descriptions: Make discoverable in /help
3. Document arguments: Always use argument-hint
4. Minimal tools: Use most restrictive allowed-tools
5. Test thoroughly: Verify all features work
6. Add comments: Explain complex logic
7. Handle errors: Consider missing arguments/files

Status

Completed enhancements:

• ✓ Plugin command patterns (${CLAUDE_PLUGIN_ROOT}, discovery, organization)
• ✓ Integration patterns (agents, skills, hooks coordination)
• ✓ Validation patterns (input, file, resource validation, error handling)

Remaining enhancements (in progress):

• Advanced workflows (multi-step command sequences)
• Testing strategies (how to test commands effectively)
• Documentation patterns (command documentation best practices)
• Marketplace considerations (publishing and distribution)

Maintenance

To update this skill:

1. Keep SKILL.md focused on core fundamentals
2. Move detailed specifications to references/
3. Add new examples/ for different use cases
4. Update frontmatter when new fields added
5. Ensure imperative/infinitive form throughout
6. Test examples work with current Claude Code

Version History

v0.1.0 (2025-01-15):

• Initial release with basic command fundamentals
• Frontmatter field reference
• 10 simple command examples
• Ready for plugin-specific pattern additions