This is an emerging class of tools that could have a significant impact over the longer term. Today, they analyze students' writing and make suggestions for improvement. That's a far sight better than simply producing a grade. Richard Byrne surveys four such tools in this article and recently featured Wordtune in a post. Other tools include Analyze My Writing, which "provides a break-down of the readability of your writing on five indices", Hemingway App, which "provides students with lots of helpful information about their text," and Slick Write. If you want to pay money there are tools like Antidote that will do the job professionally. (p.s. love the oval inset in the video).