Yes, PROMPTED is a Scrabble word!

Letter values in Scrabble US: P 3, R 1, O 1, M 3, P 3, T 1, E 1, D 2.

Is it a valid word?

PROMPTED is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

give an incentive for action
serve as the inciting cause of
assist (somebody acting or reciting) by suggesting the next words of something forgotten or imperfectly learned