"heavy (or much) vibrato" or "light vibrato". You can also specify the type of vibrato, i.e., "wide vibrato" or "narrow vibrato" or any combination thereof... "heavy, narrow vibrato," "light, wide vibrato," for example.In reality, though, when you start delving into this, it ceases at some point to be musical and becomes just an effect. So... use alterations sparingly if you want it to really mean anything.
It doesn't help that modern string players sometimes get stuck in the "molto tasteless, affected vibrato" mode.