In-Game Wiki Mod, like its name points out, provides you in-game info about Minecraft, or more particularly about blocks/items/entities, also it is being planned on a few other game mechanics. Its disadvantage is that there’s not that much to this mod apart from a fancy GUI so it’s missing is content.

Detail and Download here : In-Game Wiki Mod 1.8.9/1.7.10

See also : Mods for minecraft 1.8