Insist on knowing an agenda-- first thing.
THEN, if you feel that you are not prepared for the meeting, politely thank everyone for their time and reschedule.
"Unfortunately, we were not made aware of the agenda in advance. Regretfully, I don't feel as though I can meaningfully contribute the data/etc. I could otherwise have had available to the team."
Before that, though, I'd try a WRITTEN communication to that effect with the entire team-- insist that you be informed of the meeting's purpose.
"I appreciate that we are all busy people, and therefore I am eager to make the best use of our time on {date}'s meeting. I would like to be prepared to act as a useful member of the team and make our time together most efficient. To further this goal, what is the general purpose of the meeting scheduled for {date/time}?"
IN. WRITING.
If you get a phone call back, respond IN WRITING with a summary of that phone call.
