Command Development for Claude Code

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 c

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