# Claude Agent SDK
URL: /integrations/claude-agent-sdk

---
title: Claude Agent SDK
sidebarTitle: Claude Agent SDK
description: Build browser agents on Anthropic's first-party agent loop with in-process MCP tools.
llm: true
---

The Claude Agent SDK is the engine behind Claude Code, exposed as a Python and TypeScript library. You hand `query()` a prompt and an options object and iterate the typed messages it streams back. The Steel integration exposes a cloud browser as in-process MCP tools, so the SDK runs the agent loop and Steel handles the browser.

Available in TypeScript and Python.

### Requirements

*   **Steel API Key**: Active Steel subscription
*   **Anthropic API Key**: Access to a Claude 4 model
*   **Runtime**: Node.js 20+ or Python 3.10+
*   **Packages**: `@anthropic-ai/claude-agent-sdk` or `claude-agent-sdk`, plus `steel-sdk` and `playwright`

### Connect Steel to the Claude Agent SDK

Wrap a Steel session in a `tool()` and bundle it into an in-process MCP server:

```typescript Typescript -wc
import { createSdkMcpServer, query, tool } from "@anthropic-ai/claude-agent-sdk";
import { chromium } from "playwright";
import Steel from "steel-sdk";

const steel = new Steel({ steelAPIKey: STEEL_API_KEY });

const openSession = tool(
  "open_session",
  "Open a Steel cloud browser session.",
  {},
  async () => {
    const session = await steel.sessions.create({});
    const browser = await chromium.connectOverCDP(
      `${session.websocketUrl}&apiKey=${STEEL_API_KEY}`,
    );
    return {
      content: [
        { type: "text", text: JSON.stringify({ sessionId: session.id }) },
      ],
    };
  },
);

const steelServer = createSdkMcpServer({
  name: "steel",
  version: "1.0.0",
  tools: [openSession],
});
```

Pass the server into `query()` via `mcpServers` and pre-approve calls with `allowedTools: ["mcp__steel__*"]`. Drop the SDK's built-in tools with `tools: []` so the agent only sees Steel.

Full runnable starter: [Steel + Claude Agent SDK recipe →](/cookbook/claude-agent-sdk)

### FAQ

### Do I need to change my existing Claude Agent SDK code to use Steel?

No — Steel is exposed as in-process MCP tools. Wrap a Steel session in a `tool()`, bundle it with `createSdkMcpServer`, and your `query()` loop and message handling stay exactly the same.

### How do I connect the Claude Agent SDK to a Steel browser session?

Define a `tool()` that calls `steel.sessions.create()` and connects via `chromium.connectOverCDP()` with the session's `websocketUrl` plus `apiKey`, bundle it into an in-process MCP server with `createSdkMcpServer`, then pass that server to `query()` via `mcpServers` and pre-approve calls with `allowedTools`.

### Does the Claude Agent SDK work with Steel's proxies, stealth mode, and CAPTCHA solving?

Yes — enable them when your tool creates the session (e.g. `useProxy`, `solveCaptcha`, `stealthConfig` on `sessions.create()`). The SDK's agent loop and MCP plumbing are unaffected.

### Is the Steel integration available in both TypeScript and Python?

Yes — use `@anthropic-ai/claude-agent-sdk` for TypeScript or `claude-agent-sdk` for Python, plus `steel-sdk` and `playwright`. You'll also need an Anthropic API key with access to a Claude 4 model.


### Resources

*   [Claude Agent SDK documentation](https://platform.claude.com/docs/en/agent-sdk/overview) – Agent loop, custom MCP tools, hooks, subagents
*   [Steel Sessions API reference](/api-reference) – Programmatic session control for Steel browsers
*   [Steel Discord](https://discord.gg/steel-dev) – Get help and share what you build