Code.gs

function myFunction() {
var now = new Date();
//grab events within the next 7 days only
var future = new Date(now.getTime() + (7 * 24 * 60 * 60 * 1000));
var events = CalendarApp.getDefaultCalendar().getEvents(now, future);

events.forEach(function(event) { 
  hasgoal = false;
  hasagenda = false;
  mystatus = event.getMyStatus().toString();
  Logger.log(event.getTitle());
  // only non-recurring events where I am not the organiser and I didnt RSVP yet.
  // the INVITED also serves as a way to make sure we don't loop multiple times over the same event and spam the owner.
  if(!event.isRecurringEvent() && mystatus == 'INVITED') {
    Logger.log(event.getTitle(),mystatus);
    if(event.getDescription().match(/goal/gi) != null) {
      hasgoal = true;
    }
    if(event.getDescription().match(/agenda/gi) != null) {
      hasagenda = true;
    }
    
    if (hasagenda && hasgoal) {
      Logger.log("Has Agenda and goal. All good.");
      return;
    }
    messagebeg = "Dear valued coworker,\n\nThis is an automated message intended to politely ask, that you give meeting guests the opportunity to come prepared and leave your meetings with a result.\nWith that in mind, I would appreciate if you added "; 
    messageend = "to your meeting \"" + event.getTitle() + "\".\n\nPlease let me know when you made the changes or if you want to discuss beforehand so I can review and change my status from \"tentative\" to a firm \"yes\" or \"no\".\n\nThank you so very much and see you soon.\n\n\nCheers\nChristoph's communication automation";
    
    if (!hasagenda) {
      messagemid = "an agenda ";
      subject = event.getTitle() + " - please add agenda";
    }
    if (!hasgoal) {
      messagemid = "a meeting goal ";
      subject = event.getTitle() + " - please add meeting goal";
    }
    if (!hasgoal && !hasagenda) {
      messagemid = "an agenda & meeting goal(s) ";
      subject = event.getTitle() + " - please add agenda & meeting goal";
    }
    
    message = messagebeg + messagemid + messageend;
    emailAddress = event.getCreators()[0];
    if(emailAddress.match(/yourdomain/gi) != null) {
      Logger.log("matches");
      MailApp.sendEmail(emailAddress, subject, message);
      event.setMyStatus(CalendarApp.GuestStatus.MAYBE);
      Logger.log(emailAddress + subject + message);
    }
  }
}); 
}