For @e is no description inside commandblocks
For @p, @r and @a are discriptions, but for @e is no discription (yet) in commandblocks. They might forget to add that, but it is still a bug, because there has to be a discription for that.
For @p, @r and @a are discriptions, but for @e is no discription (yet) in commandblocks. They might forget to add that, but it is still a bug, because there has to be a discription for that.