claude-in-chrome extension never connects despite being installed, enabled, and Chrome running

Bug: claude-in-chrome extension never connects despite being installed, enabled, and Chrome running

Summary

mcp__claude-in-chrome__tabs_context_mcp (and other claude-in-chrome MCP tools) consistently return "Browser extension is not connected" across repeated retries in the same Claude Code session, even after confirming the extension is installed, enabled, and Chrome is open with tabs loaded.

Environment

• Claude Code version: 2.1.220
• OS: macOS 26.5.2 (BuildVersion 25F84)
• Extension: Claude in Chrome v1.0.85 (ID fcoeoabgfenejglbffodgkkbkcdhcgfn)
• Chrome: open, active, with tabs loaded (confirmed via user screenshot showing a live localhost:3002 page)

Steps taken (in order), each followed by a retry that still failed

1. Called tabs_context_mcp{createIfEmpty:true} — failed with "Browser extension is not connected..."
2. User ran Claude Code's /login (CLI auth) — succeeded, but unrelated to the extension's own connection; retry still failed
3. User confirmed Chrome was open with the extension icon visible in the toolbar (screenshot) — retry still failed
4. User opened chrome://extensions and confirmed: extension listed as "Claude — Claude in Chrome", version 1.0.85, toggle enabled (screenshot) — retry still failed
5. Suggested clicking the extension's toolbar icon directly to check its own sign-in/pairing status — not yet reported back by the time this ticket was drafted

At every step, tabs_context_mcp returned the identical generic error message, with no additional diagnostic detail (no distinction between "extension not installed," "not enabled," "not signed in," or "installed+enabled+signed-in but MCP bridge not paired").

Expected

Either:

• The extension connects successfully once installed, enabled, and Chrome is running with the user signed into claude.ai, OR
• If a manual pairing/sign-in step inside the extension's own popup is required, the MCP tool's error message should say so explicitly, rather than repeating "please ensure the Claude browser extension is installed and running" when both are already confirmed true.

Actual

The error message is identical and undifferentiated regardless of whether the extension is genuinely absent or whether it's installed+enabled and simply failing to pair with the CLI session. This makes it impossible for the user (or the assisting Claude Code session) to tell what to fix next without external troubleshooting.

Impact

Blocks any use of claude-in-chrome tools (screenshots, DOM reads, browser automation) for the entire session — no workaround available from inside Claude Code once the extension is confirmed installed+enabled and the connection still fails.

Suggested fix direction

Surface a more specific failure reason from the MCP bridge (e.g. "extension installed but not signed in," "extension installed but no active pairing," vs. "extension not found") so the error message can guide the user to the actual next step instead of restating already-satisfied preconditions.

Addendum: extension's own side panel works — the CLI's MCP bridge specifically fails to pair

Sharper diagnosis than the original report: the extension is not simply "not running." Its own in-browser chat panel is fully functional — it responded to a direct query with a real tab ID (2117828995, correctly identifying it was on the Admin Dashboard at localhost:3002), confirming the extension is installed, signed in, and actively doing browser automation within its own UI.

The failure is specifically in the separate MCP bridge that a Claude Code CLI session uses to reach the extension — mcp__claude-in-chrome__tabs_context_mcp still returns "Browser extension is not connected" on every retry, even though the extension is demonstrably alive and paired to the browser/account at that same moment.

This rules out "extension not installed/enabled/signed-in" as the cause and narrows it to: the CLI-session-to-extension MCP pairing/handshake is failing (or never initiating) independently of the extension's own working connection to the browser and to claude.ai.

I ran into this issue too. Sadly I don't have a solution or a workaround but I found out there are WebSocket errors in the extension's service worker console.

mcpPermissions-192xiXNg.js:2 WebSocket connection to 'wss://bridge.claudeusercontent.com/chrome/fa5cd2fe-a9f4-4c38-8667-38ed2a3c88f8' failed: Error during WebSocket handshake: Unexpected response code: 500
TD @ mcpPermissions-192xiXNg.js:2

It occurs on any network connection. Seems it's likely an issue on Anthropic's side.