Stagehand / Browserbase

browser_engine: stagehand — drives a cloud browser hosted on Browserbase through the Stagehand MCP server. Instead of low-level primitives, it exposes AI-driven, natural-language tools: navigate, act, observe, extract, plus session lifecycle (start/end).

Reference: Stagehand MCP setup.

When to use it

• You want browser automation without installing or maintaining local browsers.
• You want resilient, AI-driven steps (act("click the Sign in button"), extract("the order total")) that tolerate small DOM changes.
• You already have a Browserbase account.

Experimental — read the caveats

The Browserbase MCP surface centers on act / observe / extract / navigate. It does not expose screenshot-to-file, console-message, or network-request tools the way Playwright and Chrome DevTools do. Because result.md embeds screenshots and reports console/network failures, those sections will be best-effort on this engine. For full-fidelity QA runs, prefer Playwright (default) or Chrome DevTools.

Prerequisites

1. A Browserbase account.
2. A Browserbase API key and Project ID from the dashboard.

Configuration

This plugin uses the hosted (HTTP) Browserbase MCP. /qa-catalog:init writes this mcpServers block into each project-level browser agent:

mcpServers:
  - browserbase:
      type: http
      url: "https://mcp.browserbase.com/mcp?browserbaseApiKey=${BROWSERBASE_API_KEY}"

Export your key before launching Claude Code so the ${BROWSERBASE_API_KEY} placeholder resolves:

export BROWSERBASE_API_KEY="bb_live_..."
export BROWSERBASE_PROJECT_ID="..."   # used by some optional query params

You can also register it from the CLI instead of the inline block:

claude mcp add --transport http browserbase \
  "https://mcp.browserbase.com/mcp?browserbaseApiKey=$BROWSERBASE_API_KEY"

Optional query parameters

| Param | Purpose | |---|---| | modelName | LLM driving act/extract (default google/gemini-2.5-flash-lite). | | modelApiKey | Your own model key if you bring your own LLM. | | proxies=true | Route through Browserbase proxies. | | advancedStealth=true | Anti-bot stealth mode. | | keepAlive=true | Keep sessions warm between calls. |

Isolation & parallelism

Each spawn opens its own Browserbase cloud session, so isolation is handled server-side — no shared local profile to worry about. Mind your Browserbase plan’s concurrent-session limit when setting parallel_agents / parallel_test_runners.

Tool-name differences

On this engine the agent uses navigate, act, observe, and extract instead of the browser_* primitives. Map app actions to natural-language act calls and read state with observe / extract. See the capability map.

Settings that do not apply

• browser_channel is ignored — the cloud chooses the browser.
• browser_headless is ignored — cloud sessions are headless by nature.