Penetration is a requirement because it differentiates this tag from 'male on dickgirl' where it is a male that penetrates a dickgirl.
The dickgirl in question can be either a shemale or a futanari.
Agree with the comments, this one is pretty self describing.
Tho if you wanna give it a description give it a proper one.
Futanari shouldn't be included, it's a completely different thing.
Penetration is not a requirement in this case imo, this could involve only oral.
Domination should be another tag.
Pretty sure "Dickgirl penetrating a Male" is probably enough and fine. We don't have to dance around terms etc, its literally written on the tin. Dickgirl on male. Heck, we could describe the category by just saying "Dickgirl in Male" even.