Using the word verboseverbose may work for you. For example, "For a 1 mark question, your answer was verbose." Alternativelyfor example:
"For a 1 mark question, your answer was verbose."
As antonyms, you could use laconiclaconic or conciseconcise, e.g. "Credit will be given for a concise description of the problem."
"Credit will be given for a concise description of the problem."