help covert

COVERT
Syntax: Automatic skill

Some thieves have learned to open and close both doors and containers silently
and covertly.

See also: THIEVES 'GENERAL THIEF SKILLS'

civilized <483hp 174m 606mv 14802tnl (-5.43%) 10 PM>
You step out of the shadows.
You open a brass door.

civilized <483hp 174m 606mv 14802tnl (-5.43%) 10 PM>
You attempt to hide.

civilized <483hp 174m 606mv 14802tnl (-5.43%) 10 PM>
You step out of the shadows.
You close a brass door.

Covert never seems to fire on doors. (This is at 81%, but you get the picture).

The help file is not clear on this and neither is the command, but although you step out of the shadows, if covert is successful, no one will see that you opened the door. If you want that, you need improved hide:

IMPROVED HIDE (1421)

Syntax: Automatic Skill

This additional training in the art of hiding allows thieves to do more while remaining in the shadows. For example, thieves with this level of skill have been known to communicate with others and to open and close doors without coming out of hiding.

Improved hide without covert: You will not step out of shadows, but players in the room will see "someone opened the door".
Covert without improved hide: You will step out of the shadows, but no one will see that you opened the door.
With both: No one will see anything!