u/Chaw91

Hello !

I'm trying to use the official Gmail MCP server with Claude (https://gmailmcp.googleapis.com/mcp/v1) to allow my agent to send emails via Gmail.

Here’s everything I encountered:

• Initially, the agent could only create drafts, not send emails.
• I created my own Google Cloud OAuth app and added these scopes:
  • https://www.googleapis.com/auth/gmail.compose
  • https://www.googleapis.com/auth/gmail.send
• I also configured:
  • OAuth test users
  • Gmail API enabled
  • correct redirect URI: https://claude.ai/api/mcp/auth_callback

I had several issues that I resolved except for the third one (access forbidden) :

1. redirect_uri_mismatch
2. 403 access_denied because the app was still in testing mode
3. access forbidden – The tool is unavailable until the server is re-authorized

The strange part is this:

When I create the credential in Claude and explicitly select:
https://gmailmcp.googleapis.com/mcp/v1

Claude stores it internally as:
https://gmail.mcp.claude.com/mcp

So the MCP server URL in the session and the vault credential URL do not match.

Result:

• the credential shows as "Active"
• OAuth succeeds
• but Claude still shows:
  • Needs vault
  • or access forbidden

I recreated:

• the OAuth client
• the vault
• the credential
• the session multiple times, but the issue persists.

Has anyone successfully configured Gmail MCP with custom OAuth credentials and Gmail send permissions?

Thank you for your answers !