What is the Chant Tools application, how does it work?

According to the introduction of Benjamin Bloomfield, Chant Tools is a Tools app on the Android platform. There is currently a 1.8.29 version released on Jul 21, 2018, you can see the details below.

Offline Mass Propers
This app is an offline version of the chant tools available at http://bbloomf.github.io/jgabc/

It is mostly intended to be useful for containing the Gregorian Mass propers as well as the Gregorian Mass ordinaries as found in the Liber Usualis, and transcribed on GregoBase (http://gregobase.selapa.net) and there may be some mistakes in the chant. If you notice any, they can be corrected in GregoBase (if you go to http://bbloomf.github.io/jgabc/propers.html and find the chant with the mistake, you can click the link above the chant on the left side to get to the GregoBase version of the chant, and edit it there to fix it, or request that it be fixed.)