Stealth Browser MCP

Stealth Browser MCP

An MCP server that provides browser automation tools with built-in WAF and Cloudflare bypass. Uses agent-browser CLI with anti-detection Chrome flags and a bundled stealth extension.

Problem

Browser automation MCP servers hit the same WAF blocks as everything else. Cloudflare, LinkedIn, and Indeed detect headless Chrome before your first tool call completes. Running a browser MCP server means either accepting the blocks or maintaining a separate stealth setup that has to stay in sync.

Built

An MCP server that wraps agent-browser CLI with anti-detection flags and a stealth extension bundled inline -- no external dependency on a separate skill or extension install. Exposes 10 tools: navigate, snapshot, click, eval, type, set_viewport, screenshot, close, status, and install. The stealth extension patches browser fingerprint vectors at document_start, before any page scripts can detect them.

Outcome

Works through Cloudflare, LinkedIn, and other WAFs from any MCP-compatible agent. Zero external dependencies beyond agent-browser itself. Drop in the MCP registration, install agent-browser, and your agent has full browser automation that bypasses protections.

How it works

The stealth extension + Chrome flags trick the site into thinking you're a real user on a real Chrome browser:

Installation

1. Install dependencies

npm install -g agent-browser
agent-browser install --with-deps

2. Register the MCP server

# Find the server script
MCP_SERVER="$HOME/.hermes/skills/software-development/stealth-browser-mcp/assets/mcp_server.py"

# Register with the agent
hermes mcp add stealth-browser --command "python3 $MCP_SERVER"

Or add to config.yaml:

mcp_servers:
  stealth-browser:
    command: python3
    args: ["~/.hermes/skills/software-development/stealth-browser-mcp/assets/mcp_server.py"]
    timeout: 120

3. Start a fresh session

hermes chat --reset

The stealth browser tools will appear in the agent's tool list automatically.

Available Tools

Usage

Once registered, the agent can use the tools naturally:

"Navigate to https://www.linkedin.com/jobs/search/?keywords=admin&location=Remote" "Get the page text" "Click @e5 to see job details" "Check the stealth browser status"

Typical workflow

1. navigate to the target URL
2. snapshot to see page content with element refs (shown as @e1, @e2, etc.)
3. click on elements to interact, expand, or navigate further
4. eval to extract structured data (pricing, job listings, search results)
5. screenshot for visual confirmation
6. close when done

Job Search Example (LinkedIn, no login)

# 1. Navigate to LinkedIn jobs
navigate("https://www.linkedin.com/jobs/search/?keywords=front+office+coordinator&location=American+Fork%2C+Utah&f_TPR=r604800")

# 2. Extract job listings
eval("""
JSON.stringify(
  Array.from(document.querySelectorAll('.job-card-container')).map(c => ({
    title: c.querySelector('.job-card-list__title')?.innerText?.trim(),
    company: c.querySelector('.job-card-container__company-name')?.innerText?.trim(),
    location: c.querySelector('.job-card-container__metadata-item')?.innerText?.trim(),
    link: c.querySelector('a')?.href
  }))
)
""")

# 3. Click into a specific job
click("@e3")

# 4. Get full description
snapshot()

Self-Contained

The MCP server is fully self-contained — the stealth extension JS and manifest are bundled inline in the Python script. On startup, it extracts them to a temporary directory. No external skill or file dependencies.

Requirements

• Python 3.10+
• mcp package (pip install mcp)
• agent-browser CLI + Chromium (npm install -g agent-browser && agent-browser install --with-deps)

Troubleshooting

MCP server registers but tools return errors

# Check the server connected and found tools
hermes mcp test stealth-browser

# Check agent-browser is installed and Chromium is ready
agent-browser doctor

"Daemon already running" conflicts

If agent-browser was used manually before starting the MCP server, close orphaned daemons:

agent-browser close --all

Then the next navigate call will start a fresh session.

Eval returns "(empty result)"

The page may not have finished loading. Call navigate first, wait briefly, then eval. For pages with heavy JS rendering, use eval("document.readyState") to check if the page is fully loaded.

Server exits immediately after starting

Check stderr for import errors:

python3 /path/to/mcp_server.py 2>&1 </dev/null | head -5

Most common: pip install mcp is missing.

Chrome for Testing vs real Chromium — WAF fingerprinting gap

agent-browser downloads and uses "Google Chrome for Testing" — a special Chromium build with a distinct binary fingerprint. Aggressive WAFs like DataDome (Wellfound, some enterprise portals) can identify Chrome for Testing by its binary signatures alone, even when all stealth patches are passing (webdriver: false, clean UA, extension loaded) and the browser runs in headed mode. This is independent of any flag or extension — the binary itself is the tell.

Signs you're hitting this: The page shows "Access is temporarily restricted" / DataDome CAPTCHA despite all stealth patches passing. Your real browser on the same IP works fine.

Fix:

1. Install system Chromium:

sudo apt-get install chromium-browser

2. Override agent-browser's Chrome binary:

export AGENT_BROWSER_CHROME_PATH=/snap/bin/chromium

3. For aggressive WAFs, also use headed mode:

AGENT_BROWSER_CHROME_PATH=/snap/bin/chromium \
AGENT_BROWSER_HEADED=true \
agent-browser open <url> --args "--no-sandbox" --headed

4. For the MCP server, wrap with env:

mcp_servers:
  stealth-browser:
    command: env
    args:
      - AGENT_BROWSER_CHROME_PATH=/snap/bin/chromium
      - python3
      - /path/to/mcp_server.py
    enabled: true

Persistence: DataDome may learn the system Chromium fingerprint after the first request. Each fresh browser launch buys one successful page load. Pair with a residential proxy for recurring scraping.

Architecture

See references/architecture.md for detailed design: daemon lifecycle, JSON response unwrapping, thread safety model, command output shapes, and stealth extension internals.