The eval script on the cloak runs at pre-levels/10000 and only has the following:
Code:
doneif (field[gIsEquip].value = 0)
doneif (field[gIsAttuned].value = 0)
#situational[hero.child[skStealth],"Advantage on checks to hide",field[thingname].text]
This is always on while the item is equipped and attuned, if you need to make it only when activated or something, I think we can find some code examples to help out.