Everything I've read, it isn't really any different from a live action script. Although what's most important in animation are the storyboards, IMO. But you'd still need a script to know who (or what - could be a talking toaster), where (setting), what they're doing and what they're saying. Everything else lands in the art department.
If you're writing about fish under the sea, and they're talking, singing, playing poker on a coral table, then it's pretty obvious you're writing an animation script.