The responder is usually in charge of the bidding. These are a common set of responses after the Weak Two (in the suit x).
Response to 2x
|New suit||5/6-card suit, forcing|
|2NT||Strong asking bid||See below|
|Jump in new suit||Splinter bid|
Of course, what constitutes a minimum or a maximum and a bad or a good suit is dependent on style and needs to be discussed. A possibility is to say that a good suit requires two of the three top honors. This has the merit that responder can easily tell if 3NT is a possibility.