@RHo had some excellent suggestions on how to improve the current onboarding copy. It includes more specific messaging about what the benefits of adding tags are.
Old
Tag images to make them easier for others to find
By confirming suggested tags, you can help make images easier to search for.
Tags are computer suggested but need to be validated by humans to ensure accuracy.
Only tags that you choose will be added to images.
New
Tagging images makes them easier to find.
The following images have tags suggested by a computer, and need to be validated by a human to ensure accuracy.
By confirming tags, you will help make images easier to search for on Commons, the free license image repository that Wikipedia uses for images in its articles.
Only tags that you choose will be added to images.
