When using the Tooltip Mouseover feature in Canto, you are able to see the metadata of the asset or preview the asset. To enable the feature please see the following guide - Mouseover Preview
If you noticed that you are not able to see all the metadata upon hovering over an asset and you are using a Mac device you should be able to scroll through to see all the assets. If you do not see the scroll bar you will need to make some modifications. On your Mac you will need to go to System Preferences > General > Show scroll bars > check Always and you should be all set!