In the Metadata menu on the right side, in the the Quick Describe Set menu, Title, and Caption appear, but Headline and Description do not. Can you add Headline and Description to the Quick Describe menu in the next update? (LR 2015.7)
Also, note that the Quick Describe: Caption field is the same as the IPTC: Description field (which is also the same as the Default: Caption and Large Caption: Caption fields). They all show the same value.
And if you're technically minded and have an hour or two to spare, you don't need the plugins -- you can create your own metadata tagsets by editing a simple text file. See the Lightroom SDK.