What do you do when you receive a meeting request without agenda? Unless you are pretty confident (which is a rare case, except that you are the organizer) what is the goal of the meeting, decline it!
Meetings are necessary evil of teamwork - you want to share opinions within the team, but meetings distract you from other important things you've got to do. The key thing here is "they distract". You want to keep this distraction minimal, you want meetings to be focused and productive. And this is what agenda is all about. It helps to stay focused on the issues that need to be resolved by the team together and it allows everybody to do her homework by thinking out all of the agenda's items in advance. Meetings without agenda can take twice and trice as much time as the same meeting would take if the agenda was sent beforehand. This is especially true if the meeting is a conference call.
What would you do when you send meeting request next time?