arc-browser-mcp

MCP server that controls Arc via AppleScript, with optional CDP (remote-debugging-port) support for reading console/network events.

Requirements

• macOS (Arc AppleScript)
• Arc
• Bun

Install

bun install

Run

bun run dev

Getting started

Add the following config to your MCP client:

{
  "mcpServers": {
    "arc-devtools": {
      "command": "bunx",
      "args": ["--bun", "@alango/arc-devtools-mcp@latest"]
    }
  }
}

Note: Using @alango/arc-devtools-mcp@latest ensures that your MCP client will always use the latest version.

MCP Client configuration

Claude Code

Use the Claude Code CLI to add the Arc DevTools MCP server:

claude mcp add arc-devtools --scope user -- bunx --bun @alango/arc-devtools-mcp@latest

Claude Desktop

Add the following to your claude_desktop_config.json:

{
  "mcpServers": {
    "arc-devtools": {
      "command": "bunx",
      "args": ["--bun", "@alango/arc-devtools-mcp@latest"]
    }
  }
}

Cursor

Go to Cursor Settings -> MCP -> New MCP Server. Use the config provided above.

Copilot / VS Code

Follow the MCP install guide and use the config provided above.

Cline

Follow the guide and use the config provided above.

Windsurf

Follow the configure MCP guide and use the config provided above.

OpenCode

Add the following to your opencode.json (guide):

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "arc-devtools": {
      "type": "local",
      "command": ["bunx", "--bun", "@alango/arc-devtools-mcp@latest"]
    }
  }
}

Tools

AppleScript:

• arc_list_spaces
• arc_focus_space
• arc_list_tabs
• arc_get_active_tab
• arc_open_url
• arc_focus_tab
• arc_close_tab
• arc_reload_tab
• arc_execute_js

CDP (remote debugging):

• arc_cdp_status
• arc_cdp_connect
• arc_cdp_disconnect
• arc_cdp_get_console
• arc_cdp_get_network

Examples

List tabs:

{"tool":"arc_list_tabs","input":{}}

Open a URL:

{"tool":"arc_open_url","input":{"url":"https://example.com"}}

Execute JS in active tab:

{"tool":"arc_execute_js","input":{"javascript":"console.log('hello from mcp')"}}

Connect to CDP and read console/network:

{"tool":"arc_cdp_connect","input":{"port":9222}}

{"tool":"arc_cdp_get_console","input":{"limit":50}}

{"tool":"arc_cdp_get_network","input":{"limit":200}}

CDP (Console / Network)

CDP tools (arc_cdp_*) require Arc to be running with a remote debugging port enabled. There are two ways to set this up:

Option 1: Via arc://inspect (Recommended)

1. Open Arc and navigate to arc://inspect/#remote-debugging
2. Follow the dialog to enable remote debugging

Once enabled, the MCP server can connect to Arc automatically.

Option 2: Launch Arc with flags

If Option 1 is not available, you can launch Arc manually with the remote debugging flags:

Step 1: Quit Arc

osascript -e 'tell application "Arc" to quit'

Step 2: Relaunch Arc with flags

open -na "Arc" --args \
  --remote-debugging-port=9222 \
  --remote-allow-origins=http://127.0.0.1

If you want to allow any origin (less strict):

open -na "Arc" --args \
  --remote-debugging-port=9222 \
  --remote-allow-origins=*

Warning: Enabling the remote debugging port opens a debugging port on the running browser instance. Any application on your machine can connect to this port and control the browser. Avoid browsing sensitive websites while the debugging port is open.

Environment variables

• ARC_MCP_CDP_ORIGIN (default: http://127.0.0.1)
  • Must match what you pass to --remote-allow-origins=... (unless you use *).
• ARC_MCP_ARC_USER_DATA_DIR
  • Overrides the Arc user data dir used to read DevToolsActivePort.

Troubleshooting

• 403 Forbidden / "Rejected an incoming WebSocket connection"
  • Arc was launched without the matching --remote-allow-origins=....
  • Fix: restart Arc with --remote-allow-origins=http://127.0.0.1 (or *).
• http://127.0.0.1:9222/json/version returns 404
  • This can happen in Arc. This server falls back to DevToolsActivePort for browser WebSocket discovery.
• Port is listening but connect fails intermittently
  • Arc can restart/rotate the DevToolsActivePort UUID. Re-run arc_cdp_connect.