Though he's a familiar- and thus by contract supposed to be a helper and assistant to his summoner- he's far too lazy and far too easily distracted to really be of much help unless it's important enough to grab his attention. He'll get sent out to bring back an ingredient for a potion or a component for a spell, then come back three days later with something completely unrelated because "he forgot what he was doing." Usually something shiny like a cool rock, or some really cool looking bones he found.
It's alright though, he might not be great at his job and sure, sometimes he can be a thieving and sassy little creature, but he is Very cuddly and sometimes....quite funny. He may turn into different animals but he is always friend shaped! And being so is a great way to distract you from the fact he just swiped your loose change and now you have no idea where he went.