Some beat outputs need to be lengthy, others to be short. The only way to adapt now is to have different prompts.with only this value changed.
A better way would be to create a new variable available in the prompt system (with a default set in the prompt) and a ruler in the scene beat interface to adjust its value (bonus: a drop-down menu to select words/paragraphs/lines/verses).
It could be written like this in the prompt: {length "default=400 words""}