Command Development for Claude Code

Overview

Slash commands are frequently-used prompts defined as Markdown files that Claude executes during interactive sessions. Master command structure, frontmatter options, and dynamic features to create 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 Values: Shorthand (sonnet, opus, haiku) or full model ID (e.g., claude-sonnet-4-5-20250929) Default: Inherits from conversation

---
model: haiku
---

Use cases:

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

Shorthand names use the current default version of each model family.

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.

Syntax: The [BANG] Prefix

In actual command files, use [BANG] (exclamation mark) before backticks for pre-execution:

Current branch: [BANG]`git branch --show-current`
Files changed: [BANG]`git diff --name-only`
Environment: [BANG]`echo $NODE_ENV`

How it works:

1. Before Claude sees the command, Claude Code executes [BANG]command`` blocks
2. The bash output replaces the entire [BANG]command`` expression
3. Claude receives the expanded prompt with actual values

Example expansion:

Command file contains:

Review the [BANG]`git diff --name-only | wc -l | tr -d ' '` changed files on branch [BANG]`git branch --show-current`.

Claude receives (after pre-execution):

Review the 3 changed files on branch feature/add-auth.

Why Skill Examples Omit [BANG]

Examples in skill documentation use plain backticks without [BANG]:

Files changed: `git diff --name-only`

This is intentional. When skill content loads into Claude's context, [BANG] followed by [command name] would actually execute. Skill examples show the conceptual pattern; add the [BANG] prefix when writing actual command files.

When to use:

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

Implementation details: For advanced patterns, environment-specific configurations, and plugin integration, see references/plugin-features-reference.md

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]
)

File References

1. Explicit paths: Use clear file paths
2. Check existence: Handle missing files gracefully
3. Relative paths: Use project-relative paths
4. Glob support: Consider using Glob tool for patterns

Bash Commands

1. Limit scope: Use Bash(git:*) not Bash(*)
2. Safe commands: Avoid destructive operations
3. Handle errors: Consider command failures
4. Keep fast: Long-running commands slow invocation

Documentation

1. Add comments: Explain complex logic
2. Provide examples: Show usage in comments
3. List requirements: Document dependencies
4. Version commands: Note breaking changes

Common Patterns

Review Pattern

---
description: Review code changes
allowed-tools: Read, Bash(git:*)
---

Files changed: `git diff --name-only`

Review each file for code quality, bugs, test coverage, documentation needs.

Testing Pattern

---
description: Run tests for specific file
argument-hint: [test-file]
allowed-tools: Bash(npm:*)
---

Run tests: `npm test $1`
Analyze results and suggest fixes for failures.

Workflow Pattern

---
description: Complete PR workflow
argument-hint: [pr-number]
allowed-tools: Bash(gh:*), Read
---

PR #$1 Workflow:
1. Fetch PR: `gh pr view $1`
2. Review changes
3. Run checks
4. Approve or request changes

Troubleshooting

Command not appearing:

• Check file is in correct directory
• Verify .md extension present
• Ensure valid Markdown format
• Restart Claude Code

Arguments not working:

• Verify $1, $2 syntax correct
• Check argument-hint matches usage
• Ensure no extra spaces

Bash execution failing:

• Check allowed-tools includes Bash
• Verify command syntax in backticks
• Test command in terminal first
• Check for required permissions

File references not working:

• Verify @ syntax correct
• Check file path is valid
• Ensure Read tool allowed
• Use absolute or project-relative paths

Plugin-Specific Features

CLAUDE_PLUGIN_ROOT Variable

Plugin commands have access to ${CLAUDE_PLUGIN_ROOT}, an environment variable that resolves to the plugin's absolute path.

Purpose:

• Reference plugin files portably
• Execute plugin scripts
• Load plugin configuration
• Access plugin templates

Basic usage:

---
description: Analyze using plugin script
allowed-tools: Bash(node:*)
---

Run analysis: `node ${CLAUDE_PLUGIN_ROOT}/scripts/analyze.js $1`

Review results and report findings.

Common patterns:

# Execute plugin script
`bash ${CLAUDE_PLUGIN_ROOT}/scripts/script.sh`

# Load plugin configuration
@${CLAUDE_PLUGIN_ROOT}/config/settings.json

# Use plugin template
@${CLAUDE_PLUGIN_ROOT}/templates/report.md

# Access plugin resources
@${CLAUDE_PLUGIN_ROOT}/docs/reference.md

Why use it:

• Works across all installations
• Portable between systems
• No hardcoded paths needed
• Essential for multi-file plugins

Plugin Command Organization

Plugin commands discovered automatically from commands/ directory:

plugin-name/
├── commands/
│   ├── foo.md              # /foo (plugin:plugin-name)
│   ├── bar.md              # /bar (plugin:plugin-name)
│   └── utils/
│       └── helper.md       # /helper (plugin:plugin-name:utils)
└── plugin.json

Namespace benefits:

• Logical command grouping
• Shown in /help output
• Avoid name conflicts
• Organize related commands

Naming conventions:

• Use descriptive action names
• Avoid generic names (test, run)
• Consider plugin-specific prefix
• Use hyphens for multi-word names

Plugin Command Patterns

Configuration-based pattern:

---
description: Deploy using plugin configuration
argument-hint: [environment]
allowed-tools: Read, Bash(*)
---

Load configuration: @${CLAUDE_PLUGIN_ROOT}/config/$1-deploy.json

Deploy to $1 using configuration settings.
Monitor deployment and report status.

Template-based pattern:

---
description: Generate docs from template
argument-hint: [component]
---

Template: @${CLAUDE_PLUGIN_ROOT}/templates/docs.md

Generate documentation for $1 following template structure.

Multi-script pattern:

---
description: Complete build workflow
allowed-tools: Bash(*)
---

Build: `bash ${CLAUDE_PLUGIN_ROOT}/scripts/build.sh`
Test: `bash ${CLAUDE_PLUGIN_ROOT}/scripts/test.sh`
Package: `bash ${CLAUDE_PLUGIN_ROOT}/scripts/package.sh`

Review outputs and report workflow status.

See references/plugin-features-reference.md for detailed patterns.

Integration with Plugin Components

Commands integrate with other plugin components for powerful workflows:

• Agents: Launch plugin agents for complex tasks (agent must exist in plugin/agents/)
• Skills: Leverage plugin skills for specialized knowledge (mention skill name to trigger)
• Hooks: Coordinate with hooks that execute on tool events
• Multi-component: Combine agents, skills, and scripts in phased workflows

See references/plugin-integration.md for detailed patterns and examples.

Validation Patterns

Commands should validate inputs and resources before processing:

• Argument validation: Check required arguments match expected values
• File existence: Verify files exist before processing
• Plugin resources: Validate scripts and configs are present
• Error handling: Capture failures and provide helpful messages

Best practices: Validate early, provide helpful errors, suggest corrections.

See references/plugin-integration.md for validation examples.

---

Additional Resources

For detailed frontmatter field specifications, see references/frontmatter-reference.md. For SlashCommand tool, programmatic invocation, and permission configuration, see references/slashcommand-tool.md. For plugin-specific features and patterns, see references/plugin-features-reference.md. For plugin integration and validation patterns, see references/plugin-integration.md. For interactive user input patterns using AskUserQuestion, see references/interactive-commands.md. For multi-step command sequences and state management, see references/advanced-workflows.md. For self-documenting command patterns and maintenance docs, see references/documentation-patterns.md. For testing approaches from syntax validation to user acceptance, see references/testing-strategies.md. For distribution guidelines and quality standards, see references/marketplace-considerations.md. For command pattern examples, see examples/ directory.

Validation Scripts

Utility scripts for validating commands (execute without loading into context):

# Validate command file structure
./scripts/validate-command.sh .claude/commands/my-command.md

# Validate YAML frontmatter fields
./scripts/check-frontmatter.sh .claude/commands/my-command.md

# Validate multiple files
./scripts/validate-command.sh commands/*.md
./scripts/check-frontmatter.sh commands/*.md