Browserbase

Install the Browserbase extension for eve:

pnpm add @browserbasehq/eve

The extension requires Node.js 24 or later. A Browserbase API key covers both cloud browser sessions and Stagehand inference through Browserbase Model Gateway, so you do not need a separate model-provider key.

Add your Browserbase API key to the agent's environment:

BROWSERBASE_API_KEY=bb_live_...

Then mount the extension under agent/extensions/:

import browserbase from "@browserbasehq/eve";
export default browserbase({  apiKey: process.env.BROWSERBASE_API_KEY!,});

The filename supplies the browserbase namespace. The extension adds browserbase__search, browserbase__fetch, and persistent browser tools for creating sessions, navigating, observing, acting, extracting structured data, and running autonomous Stagehand tasks.

Use Search → Fetch → browser as an escalation path: search for sources first, fetch straightforward content without starting a session, and create a browser only when a page requires JavaScript or interaction.

You can configure the Stagehand model, session timeout, and proxies:

import browserbase from "@browserbasehq/eve";
export default browserbase({  apiKey: process.env.BROWSERBASE_API_KEY!,  model: "openai/gpt-5.4-mini",  sessionTimeoutSeconds: 900,  proxies: false,});

Browserbase uses keep-alive sessions and eve's durable per-session state to reconnect across workflow steps and function invocations. Call browserbase__stop_session when the task finishes to release billable browser time. Keep API keys out of prompts, and add approval gates around sensitive or irreversible browser actions. See the Browserbase extension package for the complete tool and configuration reference.