There is always the risk of a bite from the animal, or disease transmission to your pet. Responsible exotic animal ownership requires limiting this kind of contact. As large as possible, but no smaller than 6' x 6' x 6'. Coatis get bored easily, so the key is to constantly give them new, safe toys, food, etc., and most importantly, interaction. They love human interaction, which is okay because this is the reason for getting one in the first place.
Males make better pets than females.
Although they are smaller, the females are the dominant sex. In fact, in Coati society, the troop is run by a matriarch, and the males live apart until breeding season. Of all my Coatis, the friendliest, even to strangers, is an 8 year old male. Only feed them in their cage. DO NOT feed them from the table, or let them drink from your glass.