In order to check the readability of the content of a wiki page, one currently needs to use external tools like [[ https://readability-score.com/ | readability-score.com ]] or the [[ http://www.hemingwayapp.com | Hemingway app ]].
It would be convenient to have an interactive tool that can be invoked more easily on a given wiki page, so as to avoid constant back-and-forth copy-and-paste between the edit window and a third-party tool. This could also potentially work [[ https://www.mediawiki.org/wiki/VisualEditor_gadgets | in VisualEditor ]], if we wanted.
The code behind readability-score.com is [[ https://github.com/DaveChild/Text-Statistics | available under a free license ]], and there's also a [[ https://github.com/cgiffard/TextStatistics.js | JavaScript port ]]. This tool is specific to the English language, but I seem to remember attempts to develop formulas for other languages as well.
Improving readability using those tools is done every week to write (and simplify) [[ https://meta.wikimedia.org/wiki/Tech/News | Tech News ]]. Other areas of technical communication (like {T90263}) could also benefit from this.