Steps to reproduce:
1. Go to admin/actions configurations
2. Start creating an AI action
3. Add a length parameter of '30'
4. Add prompt 'Write 'asdf' twice' (or some other prompt differing from image description)

Actual result:
Prompt and prompt length are disregarded, there is a fallback on some kind of default 'describe image' prompt.

Expected result:
Prompt and prompt length work properly.