A tooltip may carry only supplementary copy, never required information
Aliases: hover copy · extra hint · not-required tooltip
What it is
A tooltip is a short string that appears on pointer hover or keyboard focus, filling in a meaning the visible name does not carry. Supplementary copy only is its content boundary: if the sentence is never seen, the task should still complete. Format rules, dangerous outcomes, required-field policy, and irreversible consequences placed in a tooltip hand required information to a channel that is not read by default. A tooltip is not a popover and not a coach mark. It does not even guarantee that it will appear.
Why it happens
Hover is an unstable, brief channel that many people never take. It depends on the pointer resting, a delay, and disappearance on move, and the reading window is a second or two. Putting required information there bets that the user will pause, wait, and finish the sentence. Touch users, keyboard users who have not focused that control, and anyone in a hurry lose that bet. Visible labels, help text, and error copy are stable channels. A tooltip is fit for “what is this icon,” a supplement remembered once learned, not for “without this sentence you will do the wrong thing.” Required information has to persist, because it must be present at the moment of decision; a tooltip is built not to persist.
Studying it
Put the same rule as visible copy, tooltip only, or neither, and have untrained people complete a task that depends on the rule. Record errors, spontaneous hover rate, and later recall of the rule. Independent variables: how necessary the information is, tooltip delay. Dependent variables: failure among people who never hovered. When required information lives only in the tooltip, failures should cluster on those who never hovered — a channel error, not a copy-writing error.
Where it stops holding
An icon button’s accessible name is required for a screen reader, but it should exist as the name property, not only as a visual tooltip; those are different channels. In an expert UI, shortcut hints that are already memorised may appear only on hover, because the task no longer depends on reading them. Legal text cannot go in a tooltip. Empty-state or first-use copy that looks like a tooltip but is actually persistent help should not be built as a disappearing hover layer.
Applying it
- Ask: if this sentence is removed, will a first-time user fail? If yes, put it in a label, help, or confirm — not in a tooltip.
- Restrict tooltips to expansions of a name, shortcut hints, and rarely needed unit notes.
- Put danger and irreversibility beside the action or in a confirm.
- How to check: disable pointer hover and complete the task. If failure is due to a sentence that lived only in a tooltip, that sentence was on the wrong channel.