I thought found_in objects were moved each turn into the location of the player object, when the player object is in one of the rooms in the found_in property, thus allowing them to affect the room description like any other object. However, the footnote on page 44 of the Hugo Book seems to prove me wrong:
I must have been remembering Inform when I assumed that the Library moved found_in objects to the different rooms as the player entered them.Hugo Book wrote:The found_in property allows you have an object considered in a location (i.e., a room object) without it being “physically” in that room object.
(Note -- this is for World Builder. An object representing part of the star cruiser's interior should be displayed in both the "Space" and "In Orbit" room descriptions.)