The rest of the hand is completely unknown. Could have a 6 or 7-card minor. Invitation to cue bid or splinter. The jump warns responder of a minimum hand. 2NT shows a minimum hand but both 4-card majors.
Minimum agreement shows a good hand.
A jump in agreeing a suit shows a minimum. With no agreement keep going slow even with a minimum hand. All bids are natural from this point on. Raise openers suit with support or show a balanced hand or a new suit with an unbalanced hand.