From the NannyMUD documentation

LAST CHANGE

2001-01-06

FUNCTION

NAME
        set_long - set the long description of an object


LOCATION
	This function exists in very many of the lib objects, basically it is
	used by all objects a player will encounter.

SYNTAX
	void set_long(string long)

DESCRIPTION
	This function sets the long description of the object, which is what
	players usually see when they are actively looking at something.


NOTE
	Usually, when players enter a room, they get to see the long
	description of the room, and the short description of all items in the
	room. This behaviour can be toggled by the players; in 'brief' mode
	they are presented with the short description of the room, too.


EXAMPLE
	set_long("The monkey has a red face and a long tail "+
	         "It yawns at you, showing off its sharp teeth.");