Issue Utilizing With a Delegated Gmail Account #528
Description
I'm building a script that accesses a delegated Gmail inbox to read emails and use Claude Code to generate responses based on historical sent message patterns. I have the Google MCP connected to Claude Code, but I'm hitting an issue: the Gmail API returns a 403 "Delegation denied for <requesting_user>" error when using OAuth2 (Desktop app) credentials to access a delegated inbox, even though delegation is properly configured in the web UI. It appears the API requires either domain-wide delegation or explicit client ID whitelisting by a Workspace admin, which isn't clearly documented. Can someone assist me with this?