Test your judgement
Which toolbar will a first-time user operate without guessing?
A new user needs to share this document. Pick the toolbar you think they will use correctly on the first attempt.
Version B works better here. Ask someone new to find “share” in the icon-only row and they stop and decode each glyph - is share the arrow, the boxes, the three dots? A bare icon asks them to recall a meaning they were never taught. The labelled row lets them recognise the word and act.
This is recognition over recall: it is far easier to recognise the right option when it is named in front of you than to summon it from memory. A handful of icons are near-universal (search, close), but most are a guess wearing a costume.
The honest caveat: labels cost space, and on a tight mobile bar you cannot always afford them. When you drop to icon-only, lean on the truly conventional glyphs and back them with accessible names - never assume a picture speaks for itself.
See all the checks · warm up in the glossary or test the terms on the quiz.