Crab good or bad?

[Nano]

found this little guy in an acro I bought today managed to get him out with a little shrimp convincing lol. is he good or bad? about 1cm across not one claw is larger the the other
not sure If i should banish it to the sump or put him back in the acro to hide lol
He is not hairy, but smooth, sharp claws, and a pinkish coloration
sorry the pictures not fabulous, still figuring out the dslr