[BUG] iMessage MCP extension enabled in Cowork settings but never appears in session tools

Description

The iMessage MCP extension is toggled on in Cowork settings UI (with all 4 tools listed: Search Contacts, Read iMessages, Get Unread iMessages, Send iMessage), but none of these tools are ever exposed to the Cowork session. The extension simply does not appear in the deferred tools list.

This is different from #32999 / #21737 (where the tool appeared but failed with an FDA error). Here the tool never loads at all — it is completely absent from the session.

Steps to reproduce

1. Open Claude Desktop (latest version, March 2026)
2. Go to Settings → enable iMessage extension (all 4 tools enabled)
3. Start a new Cowork session
4. Ask Claude to list available MCP tools or search for iMessage tools
5. Expected: iMessage tools appear in the deferred tools list
6. Actual: No iMessage tools found. ToolSearch for "imessage", "sms", "send message", "apple message contact" etc. all return empty results

Environment

• macOS: Apple Silicon, latest macOS
• Claude Desktop: latest version (March 29, 2026)
• Full Disk Access: granted to Claude.app (confirmed in System Settings > Privacy & Security > Full Disk Access)
• iMessage extension: should have the v0.1.11 FDA pre-check fix from #21737

What works

All other MCP extensions connect fine in the same Cowork session:

• Gmail, Slack, Google Calendar, ClickUp, Chrome, Computer Use, PagerDuty, Make.com, AWS — all present and functional

Only iMessage fails to connect silently.

What I have tried

• Restarting Cowork session multiple times
• Toggling iMessage extension off and on in settings
• Full restart of Claude Desktop
• Confirming Claude.app has Full Disk Access
• Node is NOT in Full Disk Access (per #21737 this should no longer be needed after v0.1.11)

Possibly related issues

• #20377 — Local/desktop MCP tools not exposed to Cowork (closed as Completed 2026-02-14, but iMessage still does not work)
• #21737 — Node process needs FDA for iMessage (fixed in v0.1.11, but tool does not even load in Cowork)
• #32999 — iMessage MCP fails despite FDA (duplicate of #21737, not Cowork-specific)

Expected behavior

iMessage MCP tools should appear in the Cowork session deferred tools list when the extension is enabled in settings, just like Gmail, Slack, and other extensions do.

Additional context

There is no error banner or message in the Cowork UI indicating that the iMessage extension failed to connect — it fails completely silently. Other MCP connection failures (e.g. Chrome, mcp-registry) at least show a banner. The silent failure makes debugging very difficult for users.