Unless the unobstrusiveness is the main selling point, I would drop "A small unobtrusive app that allows you to" from the description and just go with "Achieve unrivaled precision with your mouse". You could list the fact that it is unobstrusive further below.
I understand your argument, but it would make more sense if the heading had better keywords. I don't see this heading adding much SEO value.
You can always A/B titles and see if a shorter title adds value, and if so, weigh it against SEO value. SEO value isn't the only determining factor; it's optimizing the entire page, which may mean giving up SEO value in favor of optimizing something that delivers higher profits.