Antibrowser

A stdio MCP server built on cloakbrowser (stealth Chromium) that lets LLM agents open web pages and interact with them via a browser-use-style accessibility tree with numeric indices — keeping token usage low.

Features

• Persistent user profile at $HOME/.antibrowser/data-dir (cookies, localStorage, cache survive restarts).
• Accessibility-tree snapshot: LLM receives an indexed text like [1] button "Submit" and calls click(1).
• Default headless; flip to headed at runtime via set_headed(true) for debugging — profile state survives.
• 12 tools: navigate, snapshot, click, fill, press, scroll, get_text, back, forward, set_headed, set_humanize, close.

Installation

git clone <this-repo>
cd anti-browser-mcp
uv sync

cloakbrowser downloads its patched Chromium on first launch; if that fails, run:

uv run python -c "import cloakbrowser; cloakbrowser.ensure_binary()"

Configuration

Env var	Default	Meaning
ANTIBROWSER_DATA_DIR	~/.antibrowser/data-dir	Browser profile directory
ANTIBROWSER_HEADLESS	1	0 launches headed by default
ANTIBROWSER_NAV_TIMEOUT_MS	30000	Navigation timeout
ANTIBROWSER_LICENSE_KEY	unset	cloakbrowser license key (if required by your plan)
ANTIBROWSER_PROXY	unset	Proxy URL
ANTIBROWSER_HUMANIZE	0	1 enables cloakbrowser's human-like mouse/keyboard/scroll layer by default

Wiring into Claude Code

claude mcp add antibrowser -- uv --directory /path/to/anti-browser-mcp run anti-browser-mcp

Wiring into Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "antibrowser": {
      "command": "uv",
      "args": ["--directory", "/path/to/anti-browser-mcp", "run", "anti-browser-mcp"]
    }
  }
}

Usage example (in Claude)

Open example.com and tell me the main heading.

Claude will call navigate, then snapshot, then get_text(1) (or whichever index the heading got) and reply.

Manual login CLI

Before letting the LLM drive the browser, you usually need to log in to sites once. The antibrowser open command launches cloakbrowser in headed mode against the same profile the MCP server uses.

uv run antibrowser open https://github.com https://mail.google.com

A browser window opens. Log in to each site. When done, return to the terminal and press Enter — the browser closes and cookies/localStorage are persisted to your profile at ~/.antibrowser/data-dir (or $ANTIBROWSER_DATA_DIR).

Pass --humanize to enable cloakbrowser's human-like input layer (slower, randomized mouse/keyboard) — useful for sites with strict bot detection:

uv run antibrowser open --humanize https://github.com

Now when the LLM (via the MCP server) calls navigate https://github.com, the session is already authenticated.

Profile is locked

If you see:

Error: profile at ... is locked. Is the antibrowser MCP server or another 'antibrowser open' running? Close it first.

it means another process is using the profile. Chromium only allows one process per profile directory. Stop the MCP server (or close the other antibrowser open session) and retry.

Installed script

After uv sync, the entry antibrowser is installed into the venv. On Windows call it directly:

D:\path\to\anti-browser-mcp\.venv\Scripts\antibrowser.exe open https://github.com

Development

uv run pytest -q                          # all tests
uv run pytest tests/test_config.py -v     # unit only
uv run pytest -k "not persistence" -v     # skip slow persistence tests

All unit and integration tests are expected to pass locally.