# Mastra
URL: /integrations/mastra

---
title: Mastra
sidebarTitle: Mastra
description: Build typed TypeScript browser agents with Mastra's Model Router, registry, and Studio playground.
llm: true
---

[Mastra](https://mastra.ai/) is a TypeScript framework that wraps the Vercel AI SDK with its own primitives: typed `createTool` definitions with input *and* output schemas, a top-level `Mastra` registry that wires agents into storage and observability, a Model Router that turns `'anthropic/claude-haiku-4-5'` into a working client without a provider package install, and a built-in Studio playground (`mastra dev`) for chatting with your agents and replaying traces. The Steel integration runs each tool against a Steel cloud session, so the agent's tool surface is "drive a real browser" without leaving the Mastra primitives.

### Requirements

*   **Steel API Key**: Active Steel subscription
*   **Node.js**: v22.13+
*   **Packages**: `@mastra/core`, `steel-sdk`, `playwright`, `zod`
*   **Model provider key**: Anthropic, OpenAI, Google, or any other provider supported by the Mastra Model Router

### Connect Steel to Mastra

Define a `createTool` that opens a Steel session, register it on an `Agent`, and attach the agent to a top-level `Mastra` registry:

```typescript Typescript -wc
import { Mastra } from "@mastra/core";
import { Agent } from "@mastra/core/agent";
import { createTool } from "@mastra/core/tools";
import { chromium } from "playwright";
import Steel from "steel-sdk";
import { z } from "zod";

const steel = new Steel({ steelAPIKey: process.env.STEEL_API_KEY! });

const openSession = createTool({
  id: "open-session",
  description: "Open a Steel cloud browser session.",
  inputSchema: z.object({}),
  outputSchema: z.object({
    sessionId: z.string(),
    liveViewUrl: z.string(),
  }),
  execute: async () => {
    const session = await steel.sessions.create({});
    const browser = await chromium.connectOverCDP(
      `${session.websocketUrl}&apiKey=${process.env.STEEL_API_KEY}`,
    );
    return { sessionId: session.id, liveViewUrl: session.sessionViewerUrl };
  },
});

const researchAgent = new Agent({
  id: "research-agent",
  name: "Steel Research",
  instructions: "You operate a Steel cloud browser via tools. ...",
  model: "anthropic/claude-haiku-4-5",
  tools: { openSession },
});

export const mastra = new Mastra({ agents: { researchAgent } });
```

Tools are passed as a record (not an array): the keys are what the model sees as tool names. With the registry wired up, `npx mastra dev` opens Studio at `http://localhost:4111` so you can chat with `research-agent` and inspect its tool calls live.

Full runnable starter: [Steel + Mastra recipe →](/cookbook/mastra)

### FAQ

### Do I need to change my existing Mastra code to use Steel?

No — Steel lives inside a standard `createTool` definition whose `execute` opens a session and connects Playwright over CDP. Your `Agent`, the `Mastra` registry, Model Router strings, and Studio all work unchanged.

### How do I connect Mastra to a Steel browser session?

Define a `createTool` whose `execute` calls `steel.sessions.create()` and connects via `chromium.connectOverCDP()` with the session's `websocketUrl` plus `apiKey`, register it on an `Agent` via `tools`, and attach the agent to a top-level `Mastra` registry.

### Does Mastra work with Steel's proxies, stealth mode, and CAPTCHA solving?

Yes — pass the options to `sessions.create()` inside your tool (e.g. `useProxy`, `solveCaptcha`, `stealthConfig`). Mastra's tool layer is unaffected because these are Steel session settings.


### Resources

*   [Mastra documentation](https://mastra.ai/docs) – Agents, tools, workflows, memory, and Studio
*   [Mastra Model Router](https://mastra.ai/blog/model-router) – Provider-agnostic model strings
*   [Mastra Studio](https://mastra.ai/docs/studio/overview) – Local playground for agents and workflows
*   [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