Calendar MCP: The caller does not have permission

[daviddavo]

I'm trying to use Google Calendar's MCP by following this tutorial:

https://developers.google.com/workspace/calendar/api/guides/configure-mcp-server

But I when I try to use the MCP, I get the following error:

 > Can you please write the tool call and response?
✦ The tool call made was:

   1 mcp_calendar_list_events(endTime='2026-04-28T00:00:00', startTime='2026-04-27T00:00:00')

  And the response received was:

   1 {
   2     "error": "MCP tool 'list_events' reported tool error for function call: {\"name\":\"list_events\",\"args\":{\"endTime\":\"2026-04-28T00:00:00\",\"startTime\":\"2026-04-27T00:00:00\"}} with response:
     [{\"functionResponse\":{\"name\":\"list_events\",\"response\":{\"content\":[{\"type\":\"text\",\"text\":\"The caller does not have permission\"}],\"isError\":true}}}]"
   3 }

I already had a Google Cloud account and it is working in an n8n integration, I enabled the APIs and created a new oauth, logged in with /mcp auth but I get that error, why? How could I "debug" it?

[azoz-w]

Same here!