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name chrome-health-check
description Quickly checks whether the Chrome DevTools Protocol (CDP) connection is working and reports the status. Use when the user says "is chrome connected?", "check chrome", "chrome status", "test chrome", "is chrome reachable", or any variation of wanting to know if Chrome is reachable via remote debugging port 9222 before running any browser-based work (Lighthouse, screenshots, page automation, console checks, network tracing). Also use proactively before running Chrome automation tasks if there's any doubt the connection is live, or when any chrome_* tool returns "Chrome is not reachable". Covers two connection types: (1) the DevTools Protocol (chrome_* tools via port 9222) and (2) the Claude in Chrome extension bridge. If the DevTools port fix fails to resolve, also check the extension bridge (account mismatch).

Chrome Connection Health Check

Run a quick connection test. If broken, diagnose the root cause and fix it.

Step 1: Test the connection

Call tabs_context_mcp with createIfEmpty: false.

If successful (returns tab info or "no tab group exists"): → Report: "✅ Chrome is connected and ready." Stop here.

If it returns "No Chrome extension connected after discovery": → Report: "❌ Chrome extension not connected — diagnosing now…" → Proceed to Step 2.

Step 2: Diagnose — Account Mismatch (most common cause)

The #1 root cause is an account mismatch between the Desktop App and the Chrome extension. The bridge WebSocket is namespaced per user UUID — if the two sides use different accounts, they can never find each other.

Check Desktop App account

python3 -c "
import glob, re
pattern = '/Users/*/Library/Application Support/Claude/Local Storage/leveldb/*.ldb'
for f in glob.glob(pattern):
    try:
        data = open(f,'rb').read().decode('utf-8','ignore')
        email = re.search(r'[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}', data)
        uid = re.search(r'[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}', data)
        if email: print('Desktop email:', email.group())
        if uid: print('Desktop UUID:', uid.group())
    except: pass
"

Also check the bridge URL in the log:

grep "Connecting to bridge" ~/Library/Logs/Claude/main.log | tail -3

Check extension account

Navigate to: chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/options.html

The top-right shows the logged-in email. Compare it with the Desktop App account.

If they match → accounts are correct, skip to Step 3b. If they differ → account mismatch confirmed → go to Step 3a.

Step 3a: Fix Account Mismatch

3a-1: Log out the extension

On the extension options page (chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/options.html), click "Log out".

3a-2: Switch Claude.ai browser session to the correct account

  1. Navigate to https://claude.ai/logout
  2. On the login page, click "Continue with email"
  3. Enter the correct email (same as Desktop App — e.g. ms.apps@msapps.mobi)
  4. Claude.ai sends a magic link to that email
  5. Open the email inbox for that address and click the magic link:
    • For ms.apps@msapps.mobi (Zoho Workplace): https://workplace.zoho.com/#mail_app/mail/folder/inbox
    • The magic link email arrives within ~1 minute from noreply@...mail.anthropic.com
    • Subject: "Secure link to log in to Claude.ai | {timestamp}"
    • Note: ms.apps@msapps.mobi magic link emails are delivered to the michal@msapps.mobi Zoho inbox (same org)
  6. Clicking the link logs Claude.ai into the correct account in this browser

3a-3: Re-authenticate the extension

After Claude.ai is signed in with the correct account:

  • Reload chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/options.html
  • Click "Log in" — the extension OAuth uses the active Claude.ai session automatically
  • Confirm the options page now shows the correct email in the top-right

3a-4: Restart the Claude Desktop App

discoverAndSelectExtension() runs once at startup and sets discoveryComplete=true. Every subsequent tool call throws the error permanently until the app restarts.

osascript -e 'quit app "Claude"'
sleep 3
open -a Claude
sleep 5

Then retest with tabs_context_mcp.

Step 3b: Other fixes (non-account-mismatch)

If accounts match but still broken:

Extension not installed/enabled:

  • Go to chrome://extensions/ → confirm fcoeoabgfenejglbffodgkkbkcdhcgfn is enabled

Extension token expired:

  • Log out and back in on the extension options page

Bridge WebSocket down or Chrome not focused:

osascript -e 'quit app "Google Chrome"'
sleep 2
open -a "Google Chrome"
sleep 3
osascript -e 'quit app "Claude"'
sleep 2
open -a Claude

Quick Reference: MSApps Account Mapping

Side Account UUID
Claude Desktop App (correct) ms.apps@msapps.mobi da5d00b9-5ca9-40ea-a8b5-5052603ff35b
Chrome extension (correct) ms.apps@msapps.mobi da5d00b9-5ca9-40ea-a8b5-5052603ff35b
Chrome extension (wrong/old) msmobileapps@gmail.com 22a74de5-a2af-47b2-b30e-eab1eb168f03

Bridge URL: wss://bridge.claudeusercontent.com/chrome/{UUID} — both sides must share the same UUID.

Root Cause Summary (diagnosed April 2026)

Desktop App switched accounts (Apr 2) to ms.apps@msapps.mobi. Chrome extension kept old credentials (msmobileapps@gmail.com). Bridge namespaces don't overlap → discovery found nothing → discoveryComplete=true got permanently stuck. Fix: log out extension → sign Claude.ai into correct account via magic link → extension re-authenticates via OAuth → restart Desktop App.