The Join Tool tells you which records did not match (Left and Right) but it does not tell you what fields it did not match on. This could quickly help the analyst determine which fields they need to look into to determine why there are unmatched records. When joining on 5+ fields it becomes difficult to determine why some records did not match without manually inspecting each record which is time consuming. The column title could be: Unmatched Field(s) and the values should be concatenated separated by commas.