we get descriptions in the books during the battles that makes it seem like the tail could reach wayyy past the andalites head...but from the ax book cover illustrations, it seems like it cant even reach the front of him at all, let alone slash at enemies, unless he turned to face his rear towards them.
The cover of visser makes the tail more believable to its descriptions as in the stories.
I'm thinking that the tail has to be long, like say if the average adult andalite body length (minus the tail), from its buttocks to its front is similar to a small horse, like say, 1.60 meters - 1.80 meters long, then their tail; in order to reach over their head and front body from the buttocks to reach a hork-bajir throat and stuff without having to be right up close in hugging distance, would have to be like, around 3 - 5 meters long?