With the Watson Tone Analyzer service on IBM Bluemix you can discover, understand, and revise the language tones in text before you publish, send or share it. Below is a little sample how to invoke the service from WordPress via a simple Chrome extension.
Next the extension opens up the tone analyzer sample web application. I used this application since it comes with a nice visualization of the text and the tones. It even shows potentially better synonyms when clicking on specific words. As a shortcut I send the text from WordPress as URL parameter (there are certainly better ways to do this).