It's preferred that the reviewer identifies a problem and is trying to come up with a solution. The author learns most by solving it him/herself and the author has most knowledge about the subject at hand and can best predict whether a solution will cause new problems.
So, the instructions for the reviewer are:
Note:
There are many ways to save time in writing down your comments. With a very detailed checklist, a problem description could consist only of a reference to the checklist, eg "Rule 76, checklist Code, point 4." Spelling mistakes can also be shortened by marking "SP reeding" or only a highlighting.