The text of a help tag should briefly describe what an interface element does. If you find that you need more than a few words to describe the function of a control, you might want to reconsider the design of your application’s user interface.
You can define help tags in Interface Builder, where they are called tooltips. Here are some guidelines to help you create effective help tag messages.
In general, don’t name the interface element in the tag. Because a help tag is specific to a UI element, it should not be necessary to refer to by name, unless the name helps the user and isn’t available onscreen. If you do need to refer to an element by name, make sure you use the same name throughout all of your documentation.
Describe only the element that the pointer is resting on. Users expect a help tag to describe what they can do with the control; they do not expect to read about other controls or about how to perform a larger task.
Describe controls that are unique to your application. Don’t provide help tags that describe window resize controls, scrollers, or other standard Aqua controls.
Focus on the action users can perform using the control. A good way to stay focused on the action is to begin the tag with a verb, for example, “Restores default settings” or “Add or remove a language from the list”.
Use the fewest words possible. Try to keep your tags to a maximum of 60 to 75 characters. Because help tags are always on, it is important to keep your tag text unobtrusive—that is, short—and useful. A tag should present only one concept and that concept should be directly related to the interface element. You can also omit articles to limit the length of the tag. Note that localization can lengthen the text by 20 to 30 percent, which is another good reason to keep the tag short.
Use sentence-style capitalization. Sentence-style capitalization tends to appear more friendly and less formal to users (to learn more about this capitalization style, see “Capitalizing Labels and Text”).
In general, use a sentence fragment. A sentence fragment emphasizes the brevity of the help tag’s message. If the tag text must form a complete sentence, end it with the appropriate punctuation.
Consider creating contextually sensitive help tags. You can provide different text for different states a control can have, or you can provide the same text for all states. When you describe what the interface element accomplishes, you help the user understand the current state of the control even if the tag isn’t applicable to all situations.
