In writing, an argumentative text and therefore an argumentative writing prompt is one in which you are asked to provide reasons, arguments, and evidence to prove a position or opinion. This means argumentative writing prompts include statements such as "support your position/opinion" or "provide reasons in favor/against". However, in the case of "describe a time when" this prompt can not be classified within the argumentative writing as in this prompt you are asked to describe events (descriptive writing) but not to provide reasons to support an idea which is the main purpose of argumentative writing.
