MCP OAuth client resolution fails with Home Assistant: Failed to resolve OAuth client for MCP connector

API Bugs
1

Hi,

I’m trying to connect an MCP server that fronts a Home Assistant instance at https://domain.com (MCP SSE endpoint: https://domain.com/mcp_server/sse). In ChatGPT, adding this MCP server fails with:

"detail": "Failed to resolve OAuth client for MCP connector: https://domain.com/mcp_server/sse"

Home Assistant exposes the well-known OAuth metadata at https://domain.com/.well-known/oauth-authorization-server, which currently returns:

{
  "issuer": "https://domain.com",
  "authorization_endpoint": "https://domain.com/auth/authorize",
  "token_endpoint": "https://domain.com/auth/token",
  "revocation_endpoint": "https://domain.com/auth/revoke",
  "response_types_supported": ["code"],
  "service_documentation": "https://developers.home-assistant.io/docs/auth_api"
}

Note: I’m overriding the .well-known response myself because Home Assistant’s built-in endpoint has bugs (e.g., it historically didn’t include the required issuer). Even with my custom well-known (including issuer), ChatGPT still reports the error above.