Agent SDK overview

Build production AI agents with Claude Code as a library

Build AI agents that autonomously read files, run commands, search the web, edit code, and more. The Agent SDK gives you the same tools, agent loop, and context management that power Claude Code, programmable in Python and TypeScript.

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions


async def main():
async for message in query(
prompt="Find and fix the bug in auth.py",
options=ClaudeAgentOptions(allowed_tools=["Read", "Edit", "Bash"]),
):
print(message)  # Claude reads the file, finds the bug, edits it


asyncio.run(main())

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

for await (const message of query({
prompt: "Find and fix the bug in auth.ts",
options: { allowedTools: ["Read", "Edit", "Bash"] }
})) {
console.log(message); // Claude reads the file, finds the bug, edits it
}

The Agent SDK includes built-in tools for reading files, running commands, and editing code, so your agent can start working immediately without you implementing tool execution. Dive into the quickstart or explore real agents built with the SDK:

play Quickstart

Build a bug-fixing agent in minutes

star Example agents

Email assistant, research agent, and more

Get started

Install the SDK

npm install @anthropic-ai/claude-agent-sdk

pip install claude-agent-sdk

Set your API key

Get an API key from the Console, then set it as an environment variable:

export ANTHROPIC_API_KEY=your-api-key

The SDK also supports authentication via third-party API providers:

Amazon Bedrock: set CLAUDE_CODE_USE_BEDROCK=1 environment variable and configure AWS credentials
Google Vertex AI: set CLAUDE_CODE_USE_VERTEX=1 environment variable and configure Google Cloud credentials
Microsoft Azure: set CLAUDE_CODE_USE_FOUNDRY=1 environment variable and configure Azure credentials

See the setup guides for Bedrock, Vertex AI, or Azure AI Foundry for details.

Run your first agent

This example creates an agent that lists files in your current directory using built-in tools.

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions


async def main():
async for message in query(
prompt="What files are in this directory?",
options=ClaudeAgentOptions(allowed_tools=["Bash", "Glob"]),
):
if hasattr(message, "result"):
print(message.result)


asyncio.run(main())

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

for await (const message of query({
prompt: "What files are in this directory?",
options: { allowedTools: ["Bash", "Glob"] }
})) {
if ("result" in message) console.log(message.result);
}

Ready to build? Follow the Quickstart to create an agent that finds and fixes bugs in minutes.

Capabilities

Everything that makes Claude Code powerful is available in the SDK:

Your agent can read files, run commands, and search codebases out of the box. Key tools include:

Tool	What it does
Read	Read any file in the working directory
Write	Create new files
Edit	Make precise edits to existing files
Bash	Run terminal commands, scripts, git operations
Monitor	Watch a background script and react to each output line as an event
Glob	Find files by pattern (`*/.ts`, `src/*/.py`)
Grep	Search file contents with regex
WebSearch	Search the web for current information
WebFetch	Fetch and parse web page content
AskUserQuestion	Ask the user clarifying questions with multiple choice options

This example creates an agent that searches your codebase for TODO comments:

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions


async def main():
async for message in query(
prompt="Find all TODO comments and create a summary",
options=ClaudeAgentOptions(allowed_tools=["Read", "Glob", "Grep"]),
):
if hasattr(message, "result"):
print(message.result)


asyncio.run(main())

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

for await (const message of query({
prompt: "Find all TODO comments and create a summary",
options: { allowedTools: ["Read", "Glob", "Grep"] }
})) {
if ("result" in message) console.log(message.result);
}

Run custom code at key points in the agent lifecycle. SDK hooks use callback functions to validate, log, block, or transform agent behavior.

Available hooks: PreToolUse, PostToolUse, Stop, SessionStart, SessionEnd, UserPromptSubmit, and more.

This example logs all file changes to an audit file:

import asyncio
from datetime import datetime
from claude_agent_sdk import query, ClaudeAgentOptions, HookMatcher


async def log_file_change(input_data, tool_use_id, context):
file_path = input_data.get("tool_input", {}).get("file_path", "unknown")
with open("./audit.log", "a") as f:
f.write(f"{datetime.now()}: modified {file_path}\n")
return {}


async def main():
async for message in query(
prompt="Refactor utils.py to improve readability",
options=ClaudeAgentOptions(
permission_mode="acceptEdits",
hooks={
"PostToolUse": [
HookMatcher(matcher="Edit|Write", hooks=[log_file_change])
]
},
),
):
if hasattr(message, "result"):
print(message.result)


asyncio.run(main())

import { query, HookCallback } from "@anthropic-ai/claude-agent-sdk";
import { appendFile } from "fs/promises";

const logFileChange: HookCallback = async (input) => {
const filePath = (input as any).tool_input?.file_path ?? "unknown";
await appendFile("./audit.log", `${new Date().toISOString()}: modified ${filePath}\n`);
return {};
};

for await (const message of query({
prompt: "Refactor utils.py to improve readability",
options: {
permissionMode: "acceptEdits",
hooks: {
PostToolUse: [{ matcher: "Edit|Write", hooks: [logFileChange] }]
}
}
})) {
if ("result" in message) console.log(message.result);
}

Learn more about hooks →

Spawn specialized agents to handle focused subtasks. Your main agent delegates work, and subagents report back with results.

Define custom agents with specialized instructions. Include Agent in allowedTools since subagents are invoked via the Agent tool:

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions, AgentDefinition


async def main():
async for message in query(
prompt="Use the code-reviewer agent to review this codebase",
options=ClaudeAgentOptions(
allowed_tools=["Read", "Glob", "Grep", "Agent"],
agents={
"code-reviewer": AgentDefinition(
description="Expert code reviewer for quality and security reviews.",
prompt="Analyze code quality and suggest improvements.",
tools=["Read", "Glob", "Grep"],
)
},
),
):
if hasattr(message, "result"):
print(message.result)


asyncio.run(main())

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

for await (const message of query({
prompt: "Use the code-reviewer agent to review this codebase",
options: {
allowedTools: ["Read", "Glob", "Grep", "Agent"],
agents: {
"code-reviewer": {
description: "Expert code reviewer for quality and security reviews.",
prompt: "Analyze code quality and suggest improvements.",
tools: ["Read", "Glob", "Grep"]
}
}
}
})) {
if ("result" in message) console.log(message.result);
}

Messages from within a subagent's context include a parent_tool_use_id field, letting you track which messages belong to which subagent execution.

Learn more about subagents →

Connect to external systems via the Model Context Protocol: databases, browsers, APIs, and hundreds more.

This example connects the Playwright MCP server to give your agent browser automation capabilities:

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions


async def main():
async for message in query(
prompt="Open example.com and describe what you see",
options=ClaudeAgentOptions(
mcp_servers={
"playwright": {"command": "npx", "args": ["@playwright/mcp@latest"]}
}
),
):
if hasattr(message, "result"):
print(message.result)


asyncio.run(main())

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

for await (const message of query({
prompt: "Open example.com and describe what you see",
options: {
mcpServers: {
playwright: { command: "npx", args: ["@playwright/mcp@latest"] }
}
}
})) {
if ("result" in message) console.log(message.result);
}

Learn more about MCP →

Control exactly which tools your agent can use. Allow safe operations, block dangerous ones, or require approval for sensitive actions.

This example creates a read-only agent that can analyze but not modify code. allowed_tools pre-approves Read, Glob, and Grep.

import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions


async def main():
async for message in query(
prompt="Review this code for best practices",
options=ClaudeAgentOptions(
allowed_tools=["Read", "Glob", "Grep"],
),
):
if hasattr(message, "result"):
print(message.result)


asyncio.run(main())

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

for await (const message of query({
prompt: "Review this code for best practices",
options: {
allowedTools: ["Read", "Glob", "Grep"]
}
})) {
if ("result" in message) console.log(message.result);
}

Learn more about permissions →

Maintain context across multiple exchanges. Claude remembers files read, analysis done, and conversation history. Resume sessions later, or fork them to explore different approaches.

This example captures the session ID from the first query, then resumes to continue with full context:

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


async def main():
session_id = None

# First query: capture the session ID
async for message in query(
prompt="Read the authentication module",
options=ClaudeAgentOptions(allowed_tools=["Read", "Glob"]),
):
if isinstance(message, SystemMessage) and message.subtype == "init":
session_id = message.data["session_id"]

# Resume with full context from the first query
async for message in query(
prompt="Now find all places that call it",  # "it" = auth module
options=ClaudeAgentOptions(resume=session_id),
):
if isinstance(message, ResultMessage):
print(message.result)


asyncio.run(main())

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

let sessionId: string | undefined;

// First query: capture the session ID
for await (const message of query({
prompt: "Read the authentication module",
options: { allowedTools: ["Read", "Glob"] }
})) {
if (message.type === "system" && message.subtype === "init") {
sessionId = message.session_id;
}
}

// Resume with full context from the first query
for await (const message of query({
prompt: "Now find all places that call it", // "it" = auth module
options: { resume: sessionId }
})) {
if ("result" in message) console.log(message.result);
}

Learn more about sessions →

Claude Code features

The SDK also supports Claude Code's filesystem-based configuration. To use these features, set setting_sources=["project"] (Python) or settingSources: ['project'] (TypeScript) in your options.

Feature	Description	Location
Skills	Specialized capabilities defined in Markdown	`.claude/skills/*/SKILL.md`
Slash commands	Custom commands for common tasks	`.claude/commands/*.md`
Memory	Project context and instructions	`CLAUDE.md` or `.claude/CLAUDE.md`
Plugins	Extend with custom commands, agents, and MCP servers	Programmatic via `plugins` option

Compare the Agent SDK to other Claude tools

The Claude Platform offers multiple ways to build with Claude. Here's how the Agent SDK fits in:

The Anthropic Client SDK gives you direct API access: you send prompts and implement tool execution yourself. The Agent SDK gives you Claude with built-in tool execution.

With the Client SDK, you implement a tool loop. With the Agent SDK, Claude handles it:

# Client SDK: You implement the tool loop
response = client.messages.create(...)
while response.stop_reason == "tool_use":
result = your_tool_executor(response.tool_use)
response = client.messages.create(tool_result=result, **params)

# Agent SDK: Claude handles tools autonomously
async for message in query(prompt="Fix the bug in auth.py"):
print(message)

// Client SDK: You implement the tool loop
let response = await client.messages.create({ ...params });
while (response.stop_reason === "tool_use") {
const result = yourToolExecutor(response.tool_use);
response = await client.messages.create({ tool_result: result, ...params });
}

// Agent SDK: Claude handles tools autonomously
for await (const message of query({ prompt: "Fix the bug in auth.ts" })) {
console.log(message);
}

Same capabilities, different interface:

Use case	Best choice
Interactive development	CLI
CI/CD pipelines	SDK
Custom applications	SDK
One-off tasks	CLI
Production automation	SDK

Many teams use both: CLI for daily development, SDK for production. Workflows translate directly between them.

Changelog

View the full changelog for SDK updates, bug fixes, and new features:

TypeScript SDK: view CHANGELOG.md
Python SDK: view CHANGELOG.md

Reporting bugs

If you encounter bugs or issues with the Agent SDK:

TypeScript SDK: report issues on GitHub
Python SDK: report issues on GitHub

Branding guidelines

For partners integrating the Claude Agent SDK, use of Claude branding is optional. When referencing Claude in your product:

Allowed:

"Claude Agent" (preferred for dropdown menus)
"Claude" (when within a menu already labeled "Agents")
"{YourAgentName} Powered by Claude" (if you have an existing agent name)

Not permitted:

"Claude Code" or "Claude Code Agent"
Claude Code-branded ASCII art or visual elements that mimic Claude Code

Your product should maintain its own branding and not appear to be Claude Code or any Anthropic product. For questions about branding compliance, contact the Anthropic sales team.

License and terms

Use of the Claude Agent SDK is governed by Anthropic's Commercial Terms of Service, including when you use it to power products and services that you make available to your own customers and end users, except to the extent a specific component or dependency is covered by a different license as indicated in that component's LICENSE file.

Next steps

play Quickstart

Build an agent that finds and fixes bugs in minutes