i think the setter is made to stop only in jog mode not mdi mode,you need to edit the ladder to enable the G31 to be active also in mdi mode.to make this to work.
what model of Fanuc you have?
PS:if that will not work i can say that there is another trick you can use,you can use a macro program that can monitor the spindle load,if spindle load is high than usual when tool is new, that means the tool is broken but this is second plan i can help.
try first plan and we will see.