I liked going thru Stanford CS146S: How always-on agents work
Lecture recording: https://www.youtube.com/watch?v=L1OBRtfPS34
Slides: https://drive.google.com/file/d/1b8WiBk_lcB3ue-jZMLijSUMLj6S...
Note: The lecture talks mostly on always-on agents and not necessarily multi-agent system.