[BUG] Cowork MCP registry connector fails to reach ClickUp MCP server — "Couldn't reach the MCP server"

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?

After connecting the ClickUp MCP connector via OAuth in Cowork, attempting to use any ClickUp tool fails with:

"Couldn't reach the MCP server. You can check the server URL and verify the server is running."

Reference ID from the error: ofid_6719275989c5463e

The OAuth flow completes successfully, but search_mcp_registry still shows connected: false and enabledInChat: false for the ClickUp connector. Re-suggesting the connector and re-authenticating does not resolve the issue.

The same ClickUp MCP server (https://mcp.clickup.com/mcp) works correctly when connected to Claude Code locally via claude mcp add --transport http clickup https://mcp.clickup.com/mcp followed by /mcp OAuth. Only the Cowork VM connection fails.

This appears related to #27492 and #27925 — the Cowork VM cannot establish connections to remote/bridge-type MCP servers.

What Should Happen?

After completing OAuth for the ClickUp MCP connector in Cowork, the connector should show connected: true and enabledInChat: true in search_mcp_registry results, and ClickUp tools (e.g., clickup_get_workspace_hierarchy, clickup_search) should be available and functional within the Cowork session.

Error Messages/Logs

Steps to Reproduce

1. Open a Cowork session (not Claude Code CLI)
2. Use search_mcp_registry with keywords ["clickup"] — ClickUp connector appears with connected: false
3. Use suggest_connectors with the ClickUp UUID (aa5a2bca-4004-49ea-bc2b-978162587a3a) — connector card appears
4. Complete the OAuth authorization flow — OAuth succeeds
5. Attempt to use any ClickUp tool, or re-run search_mcp_registry — error: "Couldn't reach the MCP server" (reference: ofid_6719275989c5463e), connector still shows connected: false, enabledInChat: false
6. For comparison: run claude mcp add --transport http clickup https://mcp.clickup.com/mcp in Claude Code CLI, then /mcp to OAuth — works correctly, all ClickUp tools available

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Cowork (Claude Desktop, latest version as of 2026-04-15, macOS, Apple Silicon)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

This appears to be the same underlying issue as #27492 and #27925 — the Cowork VM cannot establish connections to remote/bridge-type MCP servers. The ClickUp MCP server at https://mcp.clickup.com/mcp works correctly via Claude Code CLI with HTTP transport and OAuth, confirming the server itself is functional. The failure is specific to the Cowork VM's MCP connectivity layer.

Error reference ID from Cowork: ofid_6719275989c5463e