Tutors highlight areas where the student can improve and explain why. In general, they focus on global revision (content, organization, and tone), with a smaller focus on sentence-level revision (clarifying individual sentences, addressing errors in grammar and punctuation). They check to see if there are any specific, immediately obvious issues and focus on providing feedback on how to improve these when completing the review.
Please note that the tutors will not fix every aspect of a paper. Ultimately, we are working with the writer at large, not the paper. Our goal is not simply to help the student improve this one particular piece of writing but to help the student improve as a writer for all future essays.