The workflow
Upload the character FBX you already use in Unity - Mixamo-rigged, a store asset, or your own. Type what it should do and generate. Drop the downloaded FBX into Assets: it imports as a clip on the same bones.
On the Rig tab choose Humanoid (copy the avatar from your character) or Generic for exact bone rotations. On the Animation tab set root motion and Loop Time as the clip needs, then drag it into your Animator Controller.
Why the clip fits
The motion is generated on your skeleton with your proportions, then the feet are planted and the root motion solved before export. There is no intermediate skeleton and no retarget step where the character's hands drift and the feet slide.
What to ask for
Plain present-tense English about the body, in order: "a person sneaks forward on tiptoe, then leaps sideways and rolls". Moods and manners work (tired, drunk, heavy, graceful), so do sequences of up to four beats and object handling. Up to 30 seconds per clip, one humanoid at a time.
Batching and tooling
The REST API does everything the studio does, and the MCP server exposes it as tools for Claude, Cursor and similar editors: a hundred idle variations overnight, or a prompt box inside your own tool.