Metrics for individual CSMs

My team's goals revolve around retention and advocacy. I know what the team is being measured on, however, I am looking for individual CSM metrics that roll up to the team metrics and that drive behavior that we need to have. In other words, I know that to develop a relationship, my CSMs have to be having calls with their clients regularly. While I can use a metric around meetings, what I really want is to measure useful, productive, valuable for the client meetings and not just meetings for the sake of hitting a metric.

Given this, I was hoping I could hear from you all on what you use to measure individual performance of your CSMs. If I count meetings, what do I complement that with, if anything, to drive the desired behavior. 

Thanks!