JustEnoughEffects tweaked the effect bar beside your inventory GUI. It will show several descriptive lines of detailed informations under the existing brief essentials of specific effect immediately when you put your cursor on its card.
Most recommended to use it in modpacks or with mods featuring many different kinds of potion effects, like Everlasting Abilities.
By default the mod has already provided support for Vanilla potion effects. The descriptions are designed for every single level of each effect, as is shown in the screenshots.
It has full compat with every potion effects as long as it's based on Vanilla effect mechanics. You can add custom info for them via a simple .lang file and load it into the game by Resource Loader, or even our own mods.
effect.luck.4.desc=+1 Luck per level.