claude-in-chrome MCP: 'Browser extension is not connected' despite --chrome flag and remote debugging enabled (macOS, Chrome 147)

[hanjoonchoe]

Environment

• Claude Code version: 2.1.101
• OS: macOS (Darwin 23.6.0)
• Chrome version: 147.0.7727.55
• Launch flags: claude --chrome

Description

The claude-in-chrome MCP tools consistently return "Browser extension is not connected" regardless of Chrome's remote debugging state. The tools are registered as deferred tools and their schemas load fine via ToolSearch, but every call to mcp__claude-in-chrome__tabs_context_mcp fails with the same error.

Steps to reproduce

1. Launch Claude Code with claude --chrome
2. Confirm --chrome flag is present in the process (ps aux | grep claude)
3. Load the tool schema via ToolSearch("select:mcp__claude-in-chrome__tabs_context_mcp")
4. Call mcp__claude-in-chrome__tabs_context_mcp → always returns "Browser extension is not connected"

What was tried

• Chrome UI remote debugging: Enabled via chrome://inspect/#remote-debugging — server stuck at "starting..." and never binds to port 9222
• CLI flag: --remote-debugging-port=9222 — Chrome 147 on macOS ignores this flag (no TCP listener created, confirmed via lsof). The flag appears in the process args but port 9222 never opens.
• Clean restart: Killed all Chrome processes, relaunched with the flag — same result
• Pipe mode: --remote-debugging-pipe — no effect on MCP connectivity
• claude mcp list does not show claude-in-chrome as a configured server
• claude mcp add claude-in-chrome returns "this name is reserved"

Observations

• The error message references https://claude.ai/chrome for extension installation, but it's unclear what specific extension is required (the Claude sidebar extension is already installed)
• Chrome 147 on macOS appears to sandbox the --remote-debugging-port flag — the flag is accepted but the port never binds
• The chrome://inspect/#remote-debugging toggle gets stuck at "starting..." and never transitions to an active server

Expected behavior

Clear documentation on:

1. What specific Chrome extension is required for claude-in-chrome MCP
2. Whether Chrome 147 on macOS is supported
3. Setup steps for the CLI (claude --chrome) workflow

Actual behavior

Persistent "Browser extension is not connected" error with no actionable path to resolve it.

[github-actions]

Found 3 possible duplicate issues:

1. CLI --chrome flag does not connect to native host socket #37833
2. Claude in Chrome: MCP client never connects to native host bridge socket (macOS) #45227
3. Chrome extension not connecting: Browser extension is not connected #40758

This issue will be automatically closed as a duplicate in 3 days.

• If your issue is a duplicate, please close it and 👍 the existing issue instead
• To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

[hanjoonchoe]

Additional finding: --chrome flag doesn't persist on session resume

When using claude --chrome and then resuming the session (via /exit + resume), the --chrome flag is lost. The MCP server for claude-in-chrome doesn't reinitialize on resume, making the browser integration unusable across session restarts.

Expected: Resuming a session that was started with --chrome should preserve the flag and reconnect the MCP server.

Actual: The --chrome flag is dropped on resume. Users must start a completely new session every time.

---

Feedback on duplicate detection bot

The bot tagged 3 "possible duplicates" and will auto-close this issue in 3 days. However:

• None of the linked issues have a resolution or official response
• The bot doesn't actually verify if the issues are duplicates — it just pattern-matches titles
• Auto-closing valid bug reports discourages users from reporting

If this is a known issue, a pinned FAQ or status update would be far more helpful than silently closing reports.

[arielnoy]

Here what solve it for me

⏺ Patched. tengu_quiet_fern is now true in your VS Code state. Launch VS Code and the browser/Chrome tools should appear in the Claude panel. (Caveat: the extension polls Anthropic for fresh gates and may
overwrite this — if it reverts, you'll have to reapply.)

How to do this on another computer

1. Quit VS Code completely (Cmd+Q, not just close window).

2. Find the state DB:

• macOS: ~/Library/Application Support/Code/User/globalStorage/state.vscdb
• Linux: ~/.config/Code/User/globalStorage/state.vscdb
• Windows: %APPDATA%\Code\User\globalStorage\state.vscdb

For VS Code Insiders, replace Code with Code - Insiders. For Cursor, the path is Cursor instead of Code and the key is the same.

3. Run this Python snippet (needs Python 3, no extra installs):

python3 - <<'EOF'
import os, sqlite3, json, sys

pick the right path for your OS

db = os.path.expanduser("~/Library/Application Support/Code/User/globalStorage/state.vscdb")
import shutil; shutil.copy(db, db + ".bak")
con = sqlite3.connect(db)
cur = con.cursor()
cur.execute("SELECT value FROM ItemTable WHERE key='Anthropic.claude-code'")
row = cur.fetchone()
data = json.loads(row[0]) if row and row[0] else {}
data.setdefault('experimentGates', {})['tengu_quiet_fern'] = True
cur.execute(
"INSERT INTO ItemTable(key,value) VALUES('Anthropic.claude-code', ?) "
"ON CONFLICT(key) DO UPDATE SET value=excluded.value",
(json.dumps(data),))
con.commit()
print("ok:", data['experimentGates'])
EOF

4. Launch VS Code, open the Claude panel. Confirm Chrome integration UI now appears (browser status pill in the input footer).

If it gets reset by a server fetch, just rerun the snippet — or file a feedback request to Anthropic referencing the gate name tengu_quiet_fern.

[github-actions]

Closing for now — inactive for too long. Please open a new issue if this is still relevant.