A tool reports what it did — Agent control (MCP)

Every write tool answers with its effect, not just "ok": placing footage returns where it landed on the canvas and warns when the placement loses picture; editor writes reject unknown values instead of storing them; a render reports kept, rendered and failed variants by name; frame tools say what the picture is supposed to show at that moment (an animated hook mid-entrance isn't broken). That is what lets an assistant correct itself before you look.

The same honesty covers collisions: a stack another process is rendering is listed under skipped instead of being queued behind your back, and a preview against the assistant's own running batch refuses with a pointer to render_status.

NOTE

A frame the assistant shows you comes with the timing that explains it: the hook and endcard windows on the rendered timeline, and the moment each animation is fully legible. A motion title caught mid-entrance is reported as mid-entrance, not as a defect.