Claude Code Command Development

Command Development for Claude Code

Note: The .claude/commands/ directory is a legacy format. For new skills, use the .claude/skills/<name>/SKILL.md directory format. Both are loaded identically — the only difference is file layout. See the skill-development skill for the preferred format.

Overview

Slash commands are frequently-used prompts defined as Markdown files that Claude executes during interactive sessions. Understanding command structure, frontmatter options, and dynamic features enables creating powerful, reusable workflows.

Key concepts:

• Markdown file format for commands
• YAML frontmatter for configuration
• Dynamic arguments and file references
• Bash execution for context
• Command organization and namespacing

Command Basics

What is a Slash Command?

A slash command is a Markdown file containing a prompt that Claude executes when invoked. Commands provide:

• Reusability: Define once, use repeatedly
• Consistency: Standardize common workflows
• Sharing: Distribute across team or projects
• Efficiency: Quick access to complex prompts

Critical: Commands are Instructions FOR Claude

Commands are written for agent consumption, not human consumption.

When a user invokes /command-name, the command content becomes Claude's instructions. Write commands as directives TO Claude about what to do, not as messages TO the user.

Correct approach (instructions for Claude):

Review this code for security vulnerabilities including:

- SQL injection
- XSS attacks
- Authentication issues

Provide specific line numbers and severity ratings.

Incorrect approach (messages to user):

This command will review your code for security issues.
You'll receive a report with vulnerability details.

The first example tells Claude what to do. The second tells the user what will happen but doesn't instruct Claude. Always use the first approach.

Command Locations

Project commands (shared with team):

• Location: .claude/commands/
• Scope: Available in specific project
• Label: Shown as "(project)" in /help
• Use for: Team workflows, project-specific tasks

Personal commands (available everywhere):

• Location: ~/.claude/commands/
• Scope: Available in all projects
• Label: Shown as "(user)" in /help
• Use for: Personal workflows, cross-project utilities

Plugin commands (bundled with plugins):

• Location: plugin-name/commands/
• Scope: Available when plugin installed
• Label: Shown as "(plugin-name)" in /help
• Use for: Plugin-specific functionality

File Format

Basic Structure

Commands are Markdown files with .md extension:

.claude/commands/
├── review.md           # /review command
├── test.md             # /test command
└── deploy.md           # /deploy command

Simple command:

Review this code for security vulnerabilities including:

- SQL injection
- XSS attacks
- Authentication bypass
- Insecure data handling

No frontmatter needed for basic commands.

With YAML Frontmatter

Add configuration using YAML frontmatter:

---
description: Review code for security issues
allowed-tools: Read, Grep, Bash(git:*)
model: sonnet
---

Review this code for security vulnerabilities...

YAML Frontmatter Fields

description

Purpose: Brief description shown in /help Type: String Default: First line of command prompt

---
description: Review pull request for code quality
---

Best practice: Clear, actionable description (under 60 characters)

allowed-tools

Purpose: Specify which tools command can use Type: String or Array Default: Inherits from conversation

---
allowed-tools: Read, Write, Edit, Bash(git:*)
---

Patterns:

• Read, Write, Edit - Specific tools
• Bash(git:*) - Bash with git commands only
• * - All tools (rarely needed)

Use when: Command requires specific tool access

model

Purpose: Specify model for command execution Type: String (sonnet, opus, haiku) Default: Inherits from conversation

---
model: haiku
---

Use cases:

• haiku - Fast, simple commands
• sonnet - Standard workflows
• opus - Complex analysis

argument-hint

Purpose: Document expected arguments for autocomplete Type: String Default: None

---
argument-hint: [pr-number] [priority] [assignee]
---

Benefits:

• Helps users understand command arguments
• Improves command discovery
• Documents command interface

disable-model-invocation

Purpose: Prevent SlashCommand tool from programmatically calling command Type: Boolean Default: false

---
disable-model-invocation: true
---

Use when: Command should only be manually invoked

Dynamic Arguments

Using $ARGUMENTS

Capture all arguments as single string:

---
description: Fix issue by number
argument-hint: [issue-number]
---

Fix issue #$ARGUMENTS following our coding standards and best practices.

Usage:

> /fix-issue 123
> /fix-issue 456

Expands to:

Fix issue #123 following our coding standards...
Fix issue #456 following our coding standards...

Using Positional Arguments

Capture individual arguments with $1, $2, $3, etc.:

---
description: Review PR with priority and assignee
argument-hint: [pr-number] [priority] [assignee]
---

Review pull request #$1 with priority level $2.
After review, assign to $3 for follow-up.

Usage:

> /review-pr 123 high alice

Expands to:

Review pull request #123 with priority level high.
After review, assign to alice for follow-up.

Combining Arguments

Mix positional and remaining arguments:

Deploy $1 to $2 environment with options: $3

Usage:

> /deploy api staging --force --skip-tests

Expands to:

Deploy api to staging environment with options: --force --skip-tests

File References

Using @ Syntax

Include file contents in command:

---
description: Review specific file
argument-hint: [file-path]
---

Review @$1 for:

- Code quality
- Best practices
- Potential bugs

Usage:

> /review-file src/api/users.ts

Effect: Claude reads src/api/users.ts before processing command

Multiple File References

Reference multiple files:

Compare @src/old-version.js with @src/new-version.js

Identify:

- Breaking changes
- New features
- Bug fixes

Static File References

Reference known files without arguments:

Review @package.json and @tsconfig.json for consistency

Ensure:

- TypeScript version matches
- Dependencies are aligned
- Build configuration is correct

Bash Execution in Commands

Commands can execute bash commands inline to dynamically gather context before Claude processes the command. This is useful for including repository state, environment information, or project-specific context.

When to use:

• Include dynamic context (git status, environment vars, etc.)
• Gather project/repository state
• Build context-aware workflows

Implementation details: For complete syntax, examples, and best practices, see references/plugin-features-reference.md section on bash execution. The reference includes the exact syntax and multiple working examples to avoid execution issues

Command Organization

Flat Structure

Simple organization for small command sets:

.claude/commands/
├── build.md
├── test.md
├── deploy.md
├── review.md
└── docs.md

Use when: 5-15 commands, no clear categories

Namespaced Structure

Organize commands in subdirectories:

.claude/commands/
├── ci/
│   ├── build.md        # /build (project:ci)
│   ├── test.md         # /test (project:ci)
│   └── lint.md         # /lint (project:ci)
├── git/
│   ├── commit.md       # /commit (project:git)
│   └── pr.md           # /pr (project:git)
└── docs/
    ├── generate.md     # /generate (project:docs)
    └── publish.md      # /publish (project:docs)

Benefits:

• Logical grouping by category
• Namespace shown in /help
• Easier to find related commands

Use when: 15+ commands, clear categories

Best Practices

Command Design

1. Single responsibility: One command, one task
2. Clear descriptions: Self-explanatory in /help
3. Explicit dependencies: Use allowed-tools when needed
4. Document arguments: Always provide argument-hint
5. Consistent naming: Use verb-noun pattern (review-pr, fix-issue)

Argument Handling

1. Validate arguments: Check for required arguments in prompt
2. Provide defaults: Suggest defaults when arguments missing
3. Document format: Explain expected argument format
4. Handle edge cases: Consider missing or invalid arguments

---
argument-hint: [pr-number]
---

$IF($1,
Review PR #$1,
Please provide a PR number. Usage: /review-pr [number]
)