Using description from calendar in calendar trigger

I would like to use the description of a google agenda appointment. The trigger is working, I do’t know how to get the other calendar fields (b.e. description).
Example below has the appointment but I can’t fetch the description.

Section automation.yaml:

##################################

Alarm test 1

##################################

  • id: ‘1966010022’
    alias: Test 1 Calendar alarm
    trigger:
    platform: calendar
    event: start
    entity_id: calendar.test1
    action:
    • service: variable.set_variable
      data:
      variable: alarm_tekst
      value: “Test: {{ trigger.test1.description }}”
    • service: script.sms_melding

All available Calendar trigger variables are listed in the HA Docs.