To use the faculty of describing; to give a description; as, Milton describes with uncommon force and beauty.
give a description of; "He drew an elaborate plan of attack"
In a descriptive answer you should recount, characterize, sketch or relate in narrative form.
To record, usually in writing, the basic characteristics of a species. Description is an essential ingredient in the classification of organisms.
Usually more than a mere description is expected, instead a critical review of some particular set of circumstances or events is usually expected.