FCPUTIL can be used for a number of different tasks and you are encouraged to check your online documentation on your FirstClass Server in the Administration > Server Maintenance section. Here you will find all of the different commands that can be issued by FCPUTIL
In the FirstClass App store you will find a cross platform tool (Mac and Windows) that interacts with the FCPUTIL executable to fetch the current values of real-time counters maintained by the server, such as the number of active sessions, task load, the number of files open, etc.
You can use FirstClass Health Monitor to monitor the health of your FirstClass Server.