OK. Total negative contrast (difference between deepest shadow and most intense highlight) is a result of how you expose your film, and developer temperature, concentration, and time.

With agitation you mainly change the shape of the film tonality curve, i.e. what the tonality of the film is, not the total contrast, and is something you might wish to try if you don't like how your prints come out. But start with standard agitation, like 10s every minute in a tank, or shuffle in a tray, or whatever your method is.