The ceiling — description alone stops at 5
The mark scheme prints it: an answer that is only AO3 — only what the technology does in the song — is awarded its AO3 level as its whole mark. Try it.
The five bands of the 20-mark ladder. Grey bands cannot be reached; the pin is the mark an AO3-only answer receives.
Five out of twenty — a perfect description with no evaluation stops exactly here.