Just Enough Enchantment Descriptions (JEED):
https://www.curseforge.com/minecraft/mc-mods/just-enough-effect-descriptions-jeed

All that would need to be done is to add the following to the lang files:
"effect.mowziesmobs.sunblock.description": "[description here]"
I can't give a good description because I don't know what the effect does to begin with

The other effects added by the mod don't need descriptions because somehow they have descriptions already

(Would make a pull request but I don't know how)