Slash Commands in the SDK

Slash commands provide a way to control Claude Code sessions with special commands that start with /. These commands can be sent through the SDK to perform actions like compacting context, listing context usage, or invoking custom commands. Only commands that work without an interactive terminal are dispatchable through the SDK; the system/init message lists the ones available in your session.

Discovering Available Slash Commands

The Claude Agent SDK provides information about available slash commands in the system initialization message. Access this information when your session starts:

import { query } from "@anthropic-ai/claude-agent-sdk";

for await (const message of query({
  prompt: "Hello Claude",
  options: { maxTurns: 1 }
})) {
  if (message.type === "system" && message.subtype === "init") {
    console.log("Available slash commands:", message.slash_commands);
    // Includes built-in commands plus bundled skills, for example:
    // ["clear", "compact", "context", "usage", "code-review", "verify", ...]
  }
}

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions, SystemMessage


async def main():
    async for message in query(prompt="Hello Claude", options=ClaudeAgentOptions(max_turns=1)):
        if isinstance(message, SystemMessage) and message.subtype == "init":
            print("Available slash commands:", message.data["slash_commands"])
            # Includes built-in commands plus bundled skills, for example:
            # ["clear", "compact", "context", "usage", "code-review", "verify", ...]


asyncio.run(main())

Sending Slash Commands

Send slash commands by including them in your prompt string, just like regular text. Commands that act on conversation history, such as /compact, need prior messages to work with, so the examples below ask a question first and then send the command as a follow-up to the same conversation:

import { query } from "@anthropic-ai/claude-agent-sdk";

// Build up conversation history first
try {
  for await (const message of query({
    prompt: "What does the README in this directory cover?",
    options: { maxTurns: 2 }
  })) {
    if (message.type === "result" && message.subtype === "success") {
      console.log(message.result);
    }
  }
} catch (error) {
  // A single-shot query() throws after yielding an error result,
  // so the follow-up query below still runs.
  console.error(`Session ended with an error: ${error}`);
}

// Send a slash command as a follow-up to the same conversation
for await (const message of query({
  prompt: "/compact",
  options: { continue: true, maxTurns: 1 }
})) {
  if (message.type === "result") {
    console.log("Command executed, result subtype:", message.subtype);
    // Example output: Command executed, result subtype: success
  }
}

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions, ResultMessage


async def main():
    # Build up conversation history first
    try:
        async for message in query(
            prompt="What does the README in this directory cover?",
            options=ClaudeAgentOptions(max_turns=2),
        ):
            if isinstance(message, ResultMessage) and message.subtype == "success":
                print(message.result)
    except Exception as error:
        # A single-shot query() raises after yielding an error result,
        # so the follow-up query below still runs.
        print(f"Session ended with an error: {error}")

    # Send a slash command as a follow-up to the same conversation
    async for message in query(
        prompt="/compact",
        options=ClaudeAgentOptions(continue_conversation=True, max_turns=1),
    ):
        if isinstance(message, ResultMessage):
            print("Command executed, result subtype:", message.subtype)
            # Example output: Command executed, result subtype: success


asyncio.run(main())

A query can end with an error result, for example when the maxTurns / max_turns limit is reached before the work completes. The final result message then has is_error: true and an error subtype such as error_max_turns instead of success.After yielding that final result message, the SDK raises an error, because the CLI process exits with a non-zero code.Wrap the loop in a try/catch in TypeScript or try/except in Python if your command might hit the limit, as shown in Single Message Input, or set maxTurns high enough for the work to complete. In Python, catch Exception: the SDK surfaces error results as a plain Exception.

Common Slash Commands

`/compact` - Compact conversation history

The /compact command reduces the size of your conversation history by summarizing older messages while preserving important context. Compaction needs an existing conversation with at least two prior exchanges to summarize. This example has a conversation first, then compacts it and reads the compact_boundary system message that reports the result:

import { query } from "@anthropic-ai/claude-agent-sdk";

// Compaction needs existing history, so have a conversation first
try {
  for await (const message of query({
    prompt: "Explain what this project does",
    options: { maxTurns: 2 }
  })) {
    if (message.type === "result" && message.subtype === "success") {
      console.log(message.result);
    }
  }
} catch (error) {
  // A single-shot query() throws after yielding an error result,
  // so the follow-up query below still runs.
  console.error(`Session ended with an error: ${error}`);
}

// Compact the same conversation
for await (const message of query({
  prompt: "/compact",
  options: { continue: true, maxTurns: 1 }
})) {
  if (message.type === "system" && message.subtype === "compact_boundary") {
    console.log("Compaction completed");
    console.log("Pre-compaction tokens:", message.compact_metadata.pre_tokens);
    console.log("Trigger:", message.compact_metadata.trigger);
    // Example output:
    // Compaction completed
    // Pre-compaction tokens: 1842
    // Trigger: manual
  }
}

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions, ResultMessage, SystemMessage


async def main():
    # Compaction needs existing history, so have a conversation first
    try:
        async for message in query(
            prompt="Explain what this project does",
            options=ClaudeAgentOptions(max_turns=2),
        ):
            if isinstance(message, ResultMessage) and message.subtype == "success":
                print(message.result)
    except Exception as error:
        # A single-shot query() raises after yielding an error result,
        # so the follow-up query below still runs.
        print(f"Session ended with an error: {error}")

    # Compact the same conversation
    async for message in query(
        prompt="/compact",
        options=ClaudeAgentOptions(continue_conversation=True, max_turns=1),
    ):
        if isinstance(message, SystemMessage) and message.subtype == "compact_boundary":
            print("Compaction completed")
            print("Pre-compaction tokens:", message.data["compact_metadata"]["pre_tokens"])
            print("Trigger:", message.data["compact_metadata"]["trigger"])
            # Example output:
            # Compaction completed
            # Pre-compaction tokens: 1842
            # Trigger: manual


asyncio.run(main())

A compact_boundary message only arrives when compaction ran. With nothing to summarize, /compact reports the reason instead of raising: the run still ends with a success result, no compact_boundary message is emitted, and the result text carries the message, for example Not enough messages to compact. after a single short exchange. A fresh one-shot query() call starts with empty context, so use this pattern in a session with prior turns, for example in streaming input mode or when resuming a session.

`/clear` - Reset conversation context

The /clear command resets the conversation to an empty context, so subsequent prompts start with no prior conversation history. The previous conversation remains on disk and can be returned to by passing its session ID to the resume option. This is useful in streaming input mode, where you send multiple prompts over a single connection. For one-shot query() calls, each call already starts with empty context, so sending /clear has no practical effect; start a new query() instead.

/clear in the SDK requires Claude Code v2.1.117 or later. In earlier versions it is omitted from slash_commands.

Creating Custom Slash Commands

In addition to using built-in slash commands, you can create your own custom commands that are available through the SDK. Custom commands are defined as markdown files in specific directories, similar to how subagents are configured.

The .claude/commands/ directory is the legacy format. The recommended format is .claude/skills/<name>/SKILL.md, which supports the same slash-command invocation (/name) plus autonomous invocation by Claude. See Skills for the current format. The CLI continues to support both formats, and the examples below remain accurate for .claude/commands/.

File Locations

Custom slash commands are stored in designated directories based on their scope:

Project commands: .claude/commands/ - Available only in the current project (legacy; prefer .claude/skills/)
Personal commands: ~/.claude/commands/ - Available across all your projects (legacy; prefer ~/.claude/skills/)

File Format

Each custom command is a markdown file where:

The filename (without .md extension) becomes the command name
The file content defines what the command does
Optional YAML frontmatter provides configuration

Basic Example

Create the .claude/commands directory in your project if it doesn’t exist, then create .claude/commands/refactor.md:

Refactor the selected code to improve readability and maintainability.
Focus on clean code principles and best practices.

This creates the /refactor command that you can use through the SDK.

With Frontmatter

Create .claude/commands/security-check.md:

---
allowed-tools: Read, Grep, Glob
description: Run security vulnerability scan
model: claude-opus-4-8
---

Analyze the codebase for security vulnerabilities including:
- SQL injection risks
- XSS vulnerabilities
- Exposed credentials
- Insecure configurations

Using Custom Commands in the SDK

Once defined in the filesystem, custom commands are automatically available through the SDK:

import { query } from "@anthropic-ai/claude-agent-sdk";

// Use a custom command
try {
  for await (const message of query({
    prompt: "/refactor src/auth/login.ts",
    options: { maxTurns: 3 }
  })) {
    if (message.type === "assistant") {
      console.log("Refactoring suggestions:", message.message);
    }
  }
} catch (error) {
  // A single-shot query() throws after yielding an error result,
  // so the second query below still runs.
  console.error(`Session ended with an error: ${error}`);
}

// Custom commands appear in the slash_commands list
for await (const message of query({
  prompt: "Hello",
  options: { maxTurns: 1 }
})) {
  if (message.type === "system" && message.subtype === "init") {
    console.log("Available commands:", message.slash_commands);
    // Includes built-in commands plus bundled skills and your custom commands, for example:
    // ["clear", "compact", "context", "usage", "code-review", "verify", "refactor", "security-check", ...]
  }
}

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions, AssistantMessage, SystemMessage


async def main():
    # Use a custom command
    try:
        async for message in query(
            prompt="/refactor src/auth/login.py", options=ClaudeAgentOptions(max_turns=3)
        ):
            if isinstance(message, AssistantMessage):
                for block in message.content:
                    if hasattr(block, "text"):
                        print("Refactoring suggestions:", block.text)
    except Exception as error:
        # A single-shot query() raises after yielding an error result,
        # so the second query below still runs.
        print(f"Session ended with an error: {error}")

    # Custom commands appear in the slash_commands list
    async for message in query(prompt="Hello", options=ClaudeAgentOptions(max_turns=1)):
        if isinstance(message, SystemMessage) and message.subtype == "init":
            print("Available commands:", message.data["slash_commands"])
            # Includes built-in commands plus bundled skills and your custom commands, for example:
            # ["clear", "compact", "context", "usage", "code-review", "verify", "refactor", "security-check", ...]


asyncio.run(main())

Advanced Features

Arguments and Placeholders

Custom commands support dynamic arguments using placeholders: Create .claude/commands/fix-issue.md:

---
argument-hint: [issue-number] [priority]
description: Fix a GitHub issue
---

Fix issue #$0 with priority $1.
Check the issue description and implement the necessary changes.

Use in SDK:

import { query } from "@anthropic-ai/claude-agent-sdk";

// Pass arguments to custom command
try {
  for await (const message of query({
    prompt: "/fix-issue 123 high",
    options: { maxTurns: 5 }
  })) {
    // Command will process with $0="123" and $1="high"
    if (message.type === "result" && message.subtype === "success") {
      console.log("Issue fixed:", message.result);
    }
  }
} catch (err) {
  // The run ends with an error when it reaches the maxTurns limit
  console.error("Session ended with an error:", err);
}

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions, ResultMessage


async def main():
    # Pass arguments to custom command
    try:
        async for message in query(prompt="/fix-issue 123 high", options=ClaudeAgentOptions(max_turns=5)):
            # Command will process with $0="123" and $1="high"
            if isinstance(message, ResultMessage):
                print("Issue fixed:", message.result)
    except Exception as error:
        # The run ends with an error when it reaches the max_turns limit
        print(f"Session ended with an error: {error}")


asyncio.run(main())

Bash Command Execution

Custom commands can execute bash commands and include their output: Create .claude/commands/git-commit.md:

---
allowed-tools: Bash(git add *), Bash(git status *), Bash(git commit *)
description: Create a git commit
---

## Context

- Current status: !`git status`
- Current diff: !`git diff HEAD`

## Task

Create a git commit with appropriate message based on the changes.

File References

Include file contents using the @ prefix: Create .claude/commands/review-config.md:

---
description: Review configuration files
---

Review the following configuration files for issues:
- Package config: @package.json
- TypeScript config: @tsconfig.json
- Environment config: @.env

Check for security issues, outdated dependencies, and misconfigurations.

Organization with Namespacing

Organize commands in subdirectories for better structure:

.claude/commands/
├── frontend/
│   ├── component.md      # Creates /component (project:frontend)
│   └── style-check.md     # Creates /style-check (project:frontend)
├── backend/
│   ├── api-test.md        # Creates /api-test (project:backend)
│   └── db-migrate.md      # Creates /db-migrate (project:backend)
└── review.md              # Creates /review (project)

The subdirectory appears in the command description but doesn’t affect the command name itself.

Practical Examples

Pull Request Review Command

Create .claude/commands/review-pr.md:

---
allowed-tools: Read, Grep, Glob, Bash(git diff *)
description: Comprehensive code review
---

## Changed Files
!`git diff --name-only HEAD~1`

## Detailed Changes
!`git diff HEAD~1`

## Review Checklist

Review the above changes for:
1. Code quality and readability
2. Security vulnerabilities
3. Performance implications
4. Test coverage
5. Documentation completeness

Provide specific, actionable feedback organized by priority.

Claude Code includes bundled code-review and verify skills. If you name a custom command after one of them, for example .claude/commands/code-review.md, your command shadows the bundled skill and slash_commands lists the name once.

Test Runner Command

Create .claude/commands/test.md:

---
allowed-tools: Bash, Read, Edit
argument-hint: [test-pattern]
description: Run tests with optional pattern
---

Run tests matching pattern: $ARGUMENTS

1. Detect the test framework (Jest, pytest, etc.)
2. Run tests with the provided pattern
3. If tests fail, analyze and fix them
4. Re-run to verify fixes

Use these commands through the SDK:

import { query } from "@anthropic-ai/claude-agent-sdk";

// Run code review
try {
  for await (const message of query({
    prompt: "/review-pr",
    options: { maxTurns: 3 }
  })) {
    // Process review feedback
  }
} catch (error) {
  // A single-shot query() throws after yielding an error result,
  // so the second query below still runs.
  console.error(`Session ended with an error: ${error}`);
}

// Run specific tests
for await (const message of query({
  prompt: "/test auth",
  options: { maxTurns: 5 }
})) {
  // Handle test results
}

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions


async def main():
    # Run code review
    try:
        async for message in query(prompt="/review-pr", options=ClaudeAgentOptions(max_turns=3)):
            # Process review feedback
            pass
    except Exception as error:
        # A single-shot query() raises after yielding an error result,
        # so the second query below still runs.
        print(f"Session ended with an error: {error}")

    # Run specific tests
    async for message in query(prompt="/test auth", options=ClaudeAgentOptions(max_turns=5)):
        # Handle test results
        pass


asyncio.run(main())

Agent SDK

Core concepts

Input and output

Extend with tools

Customize behavior

Control and observability

Deployment

SDK references

Discovering Available Slash Commands

Sending Slash Commands

Common Slash Commands

`/compact` - Compact conversation history

`/clear` - Reset conversation context

Creating Custom Slash Commands

File Locations

File Format

Basic Example

With Frontmatter

Using Custom Commands in the SDK

Advanced Features

Arguments and Placeholders

Bash Command Execution

File References

Organization with Namespacing

Practical Examples

Pull Request Review Command

Test Runner Command

See Also

​Discovering Available Slash Commands

​Sending Slash Commands

​Common Slash Commands

​/compact - Compact conversation history

​/clear - Reset conversation context

​Creating Custom Slash Commands

​File Locations

​File Format

​Basic Example

​With Frontmatter

​Using Custom Commands in the SDK

​Advanced Features

​Arguments and Placeholders

​Bash Command Execution

​File References

​Organization with Namespacing

​Practical Examples

​Pull Request Review Command

​Test Runner Command

​See Also

Discovering Available Slash Commands

Sending Slash Commands

Common Slash Commands

`/compact` - Compact conversation history

`/clear` - Reset conversation context

Creating Custom Slash Commands

File Locations

File Format

Basic Example

With Frontmatter

Using Custom Commands in the SDK

Advanced Features

Arguments and Placeholders

Bash Command Execution

File References

Organization with Namespacing

Practical Examples

Pull Request Review Command

Test Runner Command

See Also