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io.github.sh6drack/zen-mcp

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MCP server for Zen Browser automation via WebDriver BiDi

Source code Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

NPM package zen-mcp
Claude Code 
claude mcp add zen-mcp -e 'ZEN_DEBUG_PORT=<ZEN_DEBUG_PORT>' -- npx -y zen-mcp@1.2.1
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "zen-mcp": {
            "command": "npx",
            "args": [
                "-y",
                "zen-mcp@1.2.1"
            ],
            "env": {
                "ZEN_DEBUG_PORT": "<ZEN_DEBUG_PORT>"
            }
        }
    }
}

Environment variables

  • ZEN_DEBUG_PORT Zen Browser remote debugging port

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. zen-mcp
  2. Setup (2 minutes)
  3. 20 Tools
  4. How It Works
  5. Troubleshooting
  6. Config
  7. Requirements
  8. Test
  9. License

zen-mcp

The first MCP server for Zen Browser. Automate Zen from Claude Code, Cursor, or any MCP client.

No Selenium. No Playwright. No browser drivers. Just WebSocket.

Setup (2 minutes)

1. Start Zen with remote debugging
/Applications/Zen.app/Contents/MacOS/zen --remote-debugging-port 9222

Pro tip: Add alias zen='open /Applications/Zen.app --args --remote-debugging-port 9222' to your shell config. Then just run zen.

2. Add to Claude Code
# Option A: npm (recommended)
npm install -g zen-mcp

# Option B: Clone
git clone https://github.com/sh6drack/zen-mcp.git && cd zen-mcp && npm install

Add to ~/.claude/mcp_servers.json:

{
  "mcpServers": {
    "zen-browser": {
      "command": "zen-mcp"
    }
  }
}

If you cloned instead of npm install, use "command": "node", "args": ["/absolute/path/to/zen-mcp/server.mjs"]

Add to ~/.claude/settings.json:

{
  "permissions": {
    "allow": ["mcp__zen-browser__*"]
  }
}

That's it. Start a new Claude Code session and the zen_* tools are available.

20 Tools

Browse
ToolWhat it does
zen_navigateGo to a URL
zen_list_pagesList all open tabs
zen_select_pageSwitch to a tab
zen_new_tabOpen a new tab
zen_close_tabClose a tab
See
ToolWhat it does
zen_snapshotPage structure with selectors (filter: all/interactive/form)
zen_screenshotCapture a screenshot
zen_get_page_textGet page title, URL, and text
zen_get_form_fieldsList all form fields with labels and values
Interact
ToolWhat it does
zen_clickClick an element
zen_fillType into an input or textarea
zen_select_optionPick a dropdown option
zen_checkToggle a checkbox or radio
zen_press_keyKeyboard input (Enter, Tab, Ctrl+A, etc.)
zen_fill_formFill multiple fields at once
zen_scrollScroll the page or to an element
Utility
ToolWhat it does
zen_evaluateRun JavaScript in the page
zen_waitWait N milliseconds
zen_wait_forWait for text or element to appear
zen_reconnectForce reconnect to Zen

How It Works

Claude Code  ──stdio/MCP──>  zen-mcp  ──WebSocket/BiDi──>  Zen Browser

zen-mcp speaks WebDriver BiDi (W3C standard) directly over WebSocket. Form filling uses native value setters with input/change event dispatch so React, Vue, and Angular apps work correctly.

What Works Well
  • Navigation, clicking, form filling — rock solid, handles React/Vue/Angular
  • Screenshots and page reads — reliable content extraction
  • Tab management — open, close, switch between tabs
  • JavaScript evaluation — run any code in the page context
  • Keyboard input — shortcuts, Enter, Tab, modifier combos
Known Limitations
  • Zen inherits Firefox's WebDriver BiDi implementation, which is still maturing. Some advanced BiDi commands that work in Chrome may not be available yet.
  • Zombie sessions can only be cleared by restarting Zen (BiDi session.end is connection-scoped). zen-mcp detects this and tells you what to do.
  • No file upload or drag-and-drop support (BiDi spec limitation).
Built-in Reliability
  • Auto-reconnect with exponential backoff if WebSocket drops
  • Zombie session recovery when a previous client crashed
  • Connection retry (3 attempts with backoff)
  • Clean shutdown on SIGINT/SIGTERM to prevent orphaned sessions

Troubleshooting

ProblemFix
"Cannot connect to Zen Browser"Start Zen with --remote-debugging-port 9222
"Maximum number of active sessions"Restart Zen: killall zen && zen
Connection keeps droppingUse zen_reconnect to force a fresh connection

Config

Env VariableDefaultDescription
ZEN_DEBUG_PORT9222Zen's remote debugging port

Requirements

Test

node test-e2e.mjs   # 21 tests, needs Zen running

License

MIT

Frequently asked questions

What is io.github.sh6drack/zen-mcp?

MCP server for Zen Browser automation via WebDriver BiDi

How do I install io.github.sh6drack/zen-mcp?

It runs on your machine. In Claude Code: claude mcp add zen-mcp -e 'ZEN_DEBUG_PORT=<ZEN_DEBUG_PORT>' -- npx -y zen-mcp@1.2.1. For other clients, paste the JSON configuration from this page into their MCP settings.

Does io.github.sh6drack/zen-mcp need an API key?

Its registry entry lists no required key or secret. Some features may still need an account with the service it connects to.

Is io.github.sh6drack/zen-mcp open source?

Its code is public on GitHub, but the repository does not declare a standard license.

Who maintains io.github.sh6drack/zen-mcp?

It is published by sh6drack. AI.tn lists it but does not maintain or endorse it.

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