Hmm, I kinda thought he looked plenty big enough.O-P, yer belief is correct, that's a black rat snake.He's kinda skinny though.....you need to feed him better!
Definitely not planning any harm. The thing startled me more than anything, damn near stepped on it. I live in the woods. It's like a jungle within a few feet of either side of my house. Been here 2 years and I have not had any problems with mice or rats, haven't even seen any. Maybe there's a good explanation for thatHad one just like him in my yard a couple weeks ago.Believe he's a nice big King snake. definetely not a cottonmouth.
He will take care of the rodents running around your house, I wouldn't harm him.