Users are most likely to read and understand your balloons in either situation if you use the fewest possible words. If your balloons will be translated from English into another language, the text will most likely get longer. The text in balloons can be up to 255 characters long, or it can use up to 32 KB if you include graphics such as styled text. In order to keep translated balloons within this limit, it's a good idea to limit messages to a maximum of approximately 180 characters in English. Use active voice in your help balloons.
Active voice uses fewer words and is easier to read than passive voice.
The box is dragged to resize the window. The second example is a lot longer than the first and requires the user to think about two sentences before acting. In help balloons, you can use sentence fragments, leaving out the subject of the sentence if the item is named on screen. Put the thing that the user really wants to know first in the balloon. This sentence fragment makes it immediately clear to the user what the command will do if the user chooses it.