I am wondering on how to interpret these types of "reviews". As per the guidelines of Math reviews
Two other treatments of items are possible, but should be used sparingly. You may recommend that the item be listed without a published review, or you may recommend that the author's summary be used as the review. In the second case the quoted summary would be given above your signature, to indicate that the summary is being used on the recommendation of the reviewer. If you decide to recommend one of these options, simply put your request in the Review text box (e.g., "Publish without a review", or "Use the summary as my review"). However, in most cases, the mathematics community would prefer an insightful review to either of these two treatments.
From another post here, I understand the first option to mean "do not bother to read this article". I wonder about the second one; a first interpretation could be "everything is correct with this paper and the abstract is good enough to guide the reader". Alternative, it could mean "I didn't bothered to review it".