desktop-app-mcp-tunnel-not-a-substitute-for-permanent-registration

Claude Code Desktop can tunnel MCP servers into a workspace session without any .mcp.json or ~/.claude.json registration — this creates a false impression of permanent connectivity. When the Desktop app disconnects or the tunnel drops, all tunneled MCP tools vanish instantly and cannot be recovered mid-session. Always verify MCP connectivity is backed by explicit ~/.claude.json registration, not just Desktop tunneling.