Due to an unknown mistake, the tooltips for the vote buttons now read
Downvote this question if you find it unclear or not useful
Upvote this question if you find it clear and useful
The original and correct tooltips were
This question shows research effort; it is useful and clear
This question does not show any research effort; it is not useful or unclear
Somehow the shows research effort / does not show any research effort part was lost. However, this part is essential on Chemistry Stackexchange (and probably most other Stackexchange sites).
Such tooltips on frequently used buttons might not be important for regular users of this site who know how most things are supposed to work. However, many new users have difficulties to see and understand some basic principles of this site, as we can especially see when looking at the many homework questions that do not show any research effort.
The tooltips alone will not solve such problems; however, a little guidance here and there might help us to steer more new users in the right direction. Removing this tooltip was a step in the wrong direction.