CX can check your bags through and that will save some time, but your bags will nonetheless be off-loaded for Customs processing at JFK. You will then drop them with AA (but no need to recheck as they are already tagged to YUL) immediately after Customs, clear Security and head to your departure gate.

The connection time is tight, but whether it is doable is largely dependent on whether you are a USN and whether you have GE.