Claude in Chrome MCP: Browser extension not connected despite extension working

Description

The Claude in Chrome MCP integration fails to connect even though:

1. The Claude Chrome extension is installed and working (sidebar chat functions correctly)
2. The MCP shows as "connected" in Claude Code (/mcp command shows claude-in-chrome · ✓ connected)
3. The extension was freshly reinstalled from Chrome Web Store

Steps to Reproduce

1. Install Claude Chrome extension from Chrome Web Store
2. Open Chrome and verify the Claude sidebar works (it does - can chat with Claude)
3. Run /mcp in Claude Code - shows claude-in-chrome · ✓ connected
4. Attempt to use any claude-in-chrome MCP tool (e.g., tabs_context_mcp)

Expected Behavior

The MCP should connect to the browser and return tab information.

Actual Behavior

Every call to mcp__claude-in-chrome__tabs_context_mcp returns:

Browser extension is not connected. Please ensure the Claude browser extension is installed and running (https://claude.ai/chrome). If this is your first time connecting to Chrome, you may need to restart Chrome for the installation to take effect.

Environment

• Platform: macOS (Darwin 25.2.0)
• Chrome extension: Freshly reinstalled
• Claude Code: Latest version
• The Claude sidebar chat in Chrome works perfectly fine

Additional Context

• Previously saw CSP (Content Security Policy) errors in the extension before reinstalling
• After reinstall, CSP errors appear to be resolved
• Machine was restarted
• Chrome was restarted
• /mcp reconnection was performed multiple times

Screenshots

The Claude sidebar works and can see/interact with pages, but the MCP connection from Claude Code does not work.