Browser-based SSO Authentication Failure in MCP Tool

Bug Reports
1

Issue Description: The MCP tool fails when attempting to perform Browser-based SSO authentication, producing the error:

Error calling tool: Tool execution failed: MCP error -32000: Connection closed

Environment Details:

  • MCP server is confirmed operational
  • Tools not requiring Browser-based SSO work correctly
  • Cursor Version 0.45.7
  • VSCode Version: 1.96.2
  • OS: Darwin arm64 24.3.0

Expected Authentication Flow:

  1. Local web server initialization
  2. Default browser launch/new tab opening to IdP authentication page
  3. User authentication
  4. Browser callback to local web server

Key Question: Does Cursor sandbox MCP severs that would preventing:

  • Access to the local browser?
  • Launch of a local web server?

Impact: This issue affects multiple applications (including Snowflake) that rely on this SSO authentication pattern.

Verification Steps:

  1. MCP server connectivity confirmed working
  2. Non-SSO tools function properly
  3. SSO-dependent tools consistently fail with the specified error