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Grok Build browser MCP

Give Grok Build a browser that survives the terminal task.

Hronaut is a visible Chromium browser that runs as its own app. The local Grok Build CLI connects over native Streamable HTTP MCP, and your workspaces, sign-ins and tabs stay put after each Grok session.

Connect Grok BuildDownload Hronaut

Local MCP endpoint

http://127.0.0.1:47812/mcp

This guide is for the local Grok Build CLI running on the same computer as Hronaut. The hosted grok.com and @grok surfaces cannot reach this computer's loopback endpoint.

Step 1 · Install

Install Grok Build.

Use xAI's released binary installer, then confirm the command works. If your environment does not allow piped installers, review the installer source or follow the repository's source-build instructions.

macOS, Linux or Git Bash

Install and verify

curl -fsSL https://x.ai/cli/install.sh | bash
grok --version

Windows PowerShell

Install and verify

irm https://x.ai/cli/install.ps1 | iex
grok --version

These are the current commands published in the official Grok Build repository ↗.

Step 2 · Connect

Connect Grok Build.

Start Hronaut first. Without --scope project, Grok saves the server in your user configuration at ~/.grok/config.toml, or %USERPROFILE%\.grok\config.toml on Windows, so it works across repositories.

Authentication off (default)

Add the loopback server

grok mcp add --transport http hronaut http://127.0.0.1:47812/mcp

This command contains no credential. A new Hronaut profile starts with MCP authentication off.

Authentication on

Keep the bearer value out of TOML

[mcp_servers.hronaut]
url = "http://127.0.0.1:47812/mcp"
headers = { "Authorization" = "Bearer ${HRONAUT_MCP_TOKEN}" }

Turn on Require MCP authentication in Hronaut and load the owner token into HRONAUT_MCP_TOKEN before you start Grok. Grok expands environment variables in headers.

Do not put the token in project configuration, chat, screenshots or shell history.

Prefer editing the file? Equivalent user configuration

Authentication off · manual

~/.grok/config.toml

[mcp_servers.hronaut]
url = "http://127.0.0.1:47812/mcp"

Step 3 · Verify

Check that it works.

Use a clean workspace for this check, before Grok goes near a signed-in page.

  1. 1

    Grok sees Hronaut

    grok inspect
grok mcp list
grok mcp doctor hronaut

    Doctor checks the saved definition and the live connection, not just whether the TOML parses. In Grok's TUI, /mcps opens the MCP server panel.

  2. 2

    Hronaut sees Grok

    Open Hronaut Home. Grok should appear under Connections.

  3. 3

    Run a first browser task

    Ask: “Create a Hronaut workspace named first-check, open https://example.com inside it, and tell me the page title and workspace ID. Start with clean scratch storage.”

    Expected result: a visible first-check workspace shows Example Domain.

Security

Protect your signed-in sessions.

Keep approval on. Ask is Grok Build's default permission mode. Keep MCP browser actions reviewable when the workspace holds valuable sign-ins, and do not use always-approve for an unfamiliar repository or prompt.

Turn on authentication. A new Hronaut profile starts without authentication, so any process running as your user can control it. Enable authentication for sensitive browser profiles.

Take over for human-only steps. Pause MCP before you enter passwords, security keys, payment details or other human-only information.

Keep the endpoint local. Hosted Grok products run outside this desktop boundary. Do not expose or tunnel Hronaut to make grok.com or @grok reach the loopback server; use the local Grok Build CLI instead.

Grok Bot compatibility

What about Grok Bot?

Grok Bot does not currently provide a direct local MCP bridge to Hronaut. Grok Bot runs its agent work in an xAI-hosted cloud computer, while Grok.com custom MCP connectors require an internet-reachable URL and explicitly reject loopback addresses. In either product, 127.0.0.1 is not the computer where Hronaut is running.

What works today: run Grok Build and Hronaut on the same computer and use the setup above. That keeps Hronaut's loopback-only trust boundary and visible browser control.

Why Local Computer and quick tunnels are not the answer

Commands are not connector tools. Local Computer execution is separate from registering an MCP connector. It may let a Bot run an approved command on your computer, but xAI does not document it as a way to make Hronaut's tool catalog a native Bot connector, and Hronaut will not ask a Bot to read or copy its authentication token.

A future route needs an authenticated private relay. A future Grok Bot integration would need a narrowly scoped relay with strong client identity, revocation, request approval, and no direct exposure of the browser-control endpoint. xAI documents Enterprise Team Setup and private-network routing, but Hronaut intentionally binds its current MCP server to loopback and does not claim that deployment as supported.

Keep going

Next steps.

Give every durable browser job its own named workspace. It keeps cookies and storage apart from other workspaces and stays available to the next Grok Build task or another local MCP client. Learn how to hand off a login safely.

Download HronautAll client setup
Sources

Hronaut is an independent project and is not affiliated with or endorsed by xAI or X.