"There should be more usable tools to perform heuristic evaluations"
Evaluating interfaces is part of his daily work. He uses different sets of heuristics depending on the particular project (some times more than a single set), but the selection is always made based on his knowledge; he doesn't uses any tool to make that decision. For the final report he uses some templates he has refined during his career, but he doesn't use any specialized tool during the evaluation itself: he documents his findings in a spreadsheet.
"How can I know whether this screen makes sense or not to the user?"
When developing interfaces, sometimes she is given the detailed visual design she has to implement; but many times she has a lot of freedom to create the final layout of the page/screen (especially when working on open-source projects). She knows that there are good practices and usability techniques like heuristic evaluations to achieve better interfaces and she would like to use some of them, but she doesn't dare without some help.