Babu

Token-efficient MCP control for the Chrome session you already use—tabs, cookies, logins, and all. BABU connects any MCP-compatible coding agent to a local Chrome extension instead of launching a separate automation profile.

Why BABU

• Four compact MCP schemas by default instead of twenty repetitive browser tools.
• Progressive disclosure: browser_read returns bounded text and compact controls; browser_help reveals command details only when requested.
• Fast actions: browser_do dispatches navigation, clicks, typing, keys, scrolling, waits, screenshots, JavaScript, and loopback file uploads.
• Real browser state: uses your existing Chrome tabs and authenticated sessions.
• Portable: install directly from GitHub with uvx; every documented client uses standard MCP stdio.
• Local-first: the only network listener binds to 127.0.0.1; the extension WebSocket requires a generated pairing token.

The published MCP v2 schemas measure 567 tokens in compact mode versus 2,219 for the legacy twenty-tool surface: 74.45% less schema context per model turn (o200k_base, canonical JSON, excluding client framing).

Architecture

MCP client
   |  stdio (client-owned subprocess)
   v
BABU Python bridge
   |  authenticated WebSocket ws://127.0.0.1:8765
   v
BABU Chrome extension (MV3) -> your real Chrome tabs

Install

Prerequisites: uv and Chrome 116 or newer.

uvx --from git+https://github.com/ItMeDiaTech/[email protected] babu setup

The command exports the bundled extension to ~/.babu/extension, creates ~/.babu/token, and prints the token once for pairing.

In Chrome:

1. Open chrome://extensions.
2. Enable Developer mode.
3. Select Load unpacked and choose the printed extension directory.
4. Open the BABU extension, paste the pairing token, and select Save.

Stable Chrome no longer accepts automated --load-extension installation, so the one-time manual load is required.

Add BABU to an MCP client

Use this stdio launch definition:

{
  "command": "uvx",
  "args": [
    "--from",
    "git+https://github.com/ItMeDiaTech/[email protected]",
    "babu",
    "mcp"
  ]
}

Exact commands and config files for Hermes, Codex, Claude Code, Cursor, VS Code, Zed, ZCode, Gemini CLI, OpenCode, Cline, Windsurf, Pi, and Agent Prime are in docs/CLIENTS.md.

Only one BABU process can own WebSocket port 8765 at a time. Close another BABU-enabled harness before starting a new one.

MCP tools

Tool	Purpose
browser_health	Connection, active-tab context, and optional full tab inventory
browser_read	Bounded page text and/or compact actionable element indices
browser_do	Validated dispatcher for browser actions
browser_help	On-demand command and parameter catalog

browser_do commands:

list_tabs, get_active_tab, open_tab, close_tab, activate_tab, navigate,
get_state, snapshot, click, hover, type, select, press, scroll, extract_text, screenshot,
eval, upload_files, wait_for, back, forward, reload

Recommended flow:

1. Call browser_read with a relevant query.
2. Pass the returned element index to browser_do with click or type.
3. Re-read after navigation or major DOM changes because indices are document-local.
4. Use browser_help only when a command's parameters are unclear.

Screenshots are saved to the system temporary directory by default; base64 image bytes are omitted from model context unless include_data_url=true is explicit.

CLI utilities

babu setup [--force]            # export/update extension and create token
babu token                      # print the current pairing token
babu mcp                        # stdio MCP server, compact profile
babu relay list_tabs            # direct browser command without an MCP client
babu relay navigate '{"url":"https://example.com"}'

babu relay is useful for minimal harnesses that prefer CLI tools over MCP.

Tool profiles

• compact (default): the four tools above.
• legacy: twenty direct browser tools for clients that prefer one schema per action.
• all: both surfaces.

Select a profile with --tool-profile compact|legacy|all or BABU_TOOL_PROFILE.

Security

BABU controls the logged-in browser profile, so treat it as a powerful local tool.

• The WebSocket listener binds only to 127.0.0.1; MCP travels over stdio.
• Chrome-extension origins and client roles are validated.
• The extension-to-bridge channel uses a 256-bit token stored at ~/.babu/token.
• The extension popup can disable all control immediately.
• Password, OTP, and payment fields are redacted from routine reads.
• browser_eval executes JavaScript in the page's main world by design.
• File upload accepts only bounded direct loopback HTTP(S) URLs with no credentials.

Review every MCP tool invocation and use each client's approval controls.

Limitations

• Chrome internal pages, the Web Store, PDF viewer, unloaded tabs, and controls inside iframes or shadow roots cannot be driven.
• Strict page CSP can block browser_eval; DOM read/click/type tools still work.
• browser_press supports Enter, Tab, and synthetic Escape; use browser_type for text.
• The unpacked extension must be reloaded from chrome://extensions after an update.
• The server is single-client and single-browser-extension by design.

Update

uvx --from git+https://github.com/ItMeDiaTech/[email protected] babu setup --force

Reload BABU on chrome://extensions, then restart the MCP client. Change the Git tag in your client config when adopting a newer release.

License

MIT