Browser extension connection fails despite correct setup

Environment:

• OS: macOS 26.2
• Claude Code version: 2.1.39
• Chrome version: 144.0.7559.133
• Browser extension: Claude in Chrome (Beta) v1.0.47
• Extension installed and verified via chrome://extensions/

MCP Configuration:

{
  "mcpServers": {
    "claude-in-chrome": {
      "command": "claude",
      "args": ["--claude-in-chrome-mcp"]
    }
  }
}

Issue Description:

Browser extension is installed, enabled, and Chrome is logged into claude.ai with the same account as Claude Code, but mcp__claude-in-chrome__tabs_context_mcp consistently returns "Browser extension is not connected" error.

Steps to Reproduce:

1. Install Claude in Chrome extension (https://claude.ai/chrome)
2. Verify extension is enabled in chrome://extensions/
3. Verify logged into claude.ai with same account
4. Add MCP config to ~/.claude/mcp.json as shown above
5. Restart Claude Code (tried both claude and claude --chrome, both fail)
6. Restart Chrome completely
7. Call mcp__claude-in-chrome__tabs_context_mcp

Expected Behavior:

Connection established, browser tabs returned.

Actual Behavior:

Browser extension is not connected. Please ensure the Claude browser extension is installed and running (https://claude.ai/chrome), and that you are logged into claude.ai with the same account as Claude Code.

Troubleshooting Attempted:

• ✅ Extension enabled in chrome://extensions/
• ✅ Site access: "On all sites"
• ✅ All permissions granted (read/change data, notifications, downloads, native messaging, tab groups)
• ✅ Logged into claude.ai (verified single account)
• ✅ Service worker active (no errors in DevTools console)
• ✅ MCP config exists in ~/.claude/mcp.json
• ✅ MCP process running (ps aux shows claude --claude-in-chrome-mcp)
• ✅ Chrome completely restarted multiple times
• ✅ Claude Code completely restarted (clean start)
• ✅ Tried both claude and claude --chrome startup modes
• ❌ Connection still fails

MCP Process Status:

m   15414   0.1  1.1  /opt/homebrew/Caskroom/claude-code/2.1.39/claude --claude-in-chrome-mcp