[BUG] Cowork workspace times out on startup when MCP server is present in config (Windows 11 Home)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

What's wrong?
Cowork workspace fails to start with "Request timed out" whenever an MCP server entry is present in claude_desktop_config.json. Removing the MCP entry from the config restores Cowork. The same MCP server works correctly in Chat mode.

Environment

• Claude Desktop version: [check Help > About and paste here]
• OS: Windows 11 Home
• MCP server: @vantasdk/vanta-mcp-server (installed globally via npm)

Steps to reproduce

1. Install @vantasdk/vanta-mcp-server globally
2. Add MCP entry to claude_desktop_config.json
3. Open Claude Desktop and switch to Cowork
4. Observe: "Failed to start Claude's workspace — Request timed out"
5. Remove MCP entry from config and restart
6. Observe: Cowork starts successfully

Actual behaviour
Cowork times out on startup when any MCP server is present in the config. The MCP server itself starts correctly (confirmed by running it directly in Command Prompt).

Workaround
Remove the MCP entry from config — but this means choosing between Cowork and MCP in Chat. No way to have both.

Additional context
This is similar to issues #24918, #25206, and #27801. The MCP server runs successfully standalone and works in Chat mode — the timeout appears specific to Cowork's VM attempting to reach or initialise host-side MCP servers on startup.

What Should Happen?

Cowork should start successfully regardless of MCP servers configured for Chat mode, or provide a way to scope MCP servers per mode.

Error Messages/Logs

Cowork times out on startup when any MCP server is present in the config. The MCP server itself starts correctly (confirmed by running it directly in Command Prompt).

Steps to Reproduce

1. Install @vantasdk/vanta-mcp-server globally
2. Add MCP entry to claude_desktop_config.json
3. Open Claude Desktop and switch to Cowork
4. Observe: "Failed to start Claude's workspace — Request timed out"
5. Remove MCP entry from config and restart
6. Observe: Cowork starts successfully

Claude Model

Sonnet (default)

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.76

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

This is similar to issues #24918, #25206, and #27801. The MCP server runs successfully standalone and works in Chat mode — the timeout appears specific to Cowork's VM attempting to reach or initialise host-side MCP servers on startup.