Stairs should show any annotation of the level they lead to. Probably not by default, instead when using the nearlook and/or farlook command.

E.g. “There is a staircase down to level 2 (MUMAK BY THE STAIRS!!) here.”

Nearlooking while standing on a crystal chest will show the contents of the chest, even if it remains locked (because it’s see-through). Possibly it only shows whether there is anything in the chest, or it’s empty.