Mag timers are already in the game using the /magtimer 1 or 2 command
Item Drop checkers (see items on the ground before you pick them up) are also allowed, though I'm not sure if all of them are. I will attach one that Soly made and help with installing it if I can remember how.
As for things that tell you monster health...I've never heard of someone using it, and I wouldn't use one until you get a 100% answer from a GM, though I would guess that they are not allowed
Lemme know if you have any questions