By default in Firefox, when using folders in the bookmarks toolbar, there are no tooltips for the folders, only for the bookmarks themselves. For a large number of bookmark folders in the toolbar, it is common to suppress the Name label to the right, for instance with a userstyle, in order to have more room. The folders all look alike without their labels, and although Bookmark Favicon Changer can be used to differentiate them with icons, the option to have the folder Name appear in a tooltip is very convenient.
The Multirow Bookmarks Toolbar Plus 1.2 addon can be used to provide the tooltips, as well as more rows for folders, but it comes with bundled adware & is therefore objectionable.
Installing this Places' addon instead can provide tooltips with the folder Name visible, but only if the Description field is selected in its options, and a Description is entered into the folder Properties. If there is no Description set for the folder then the tooltip does not appear, even if the addon's Description option is checked. There is no checkbox in the options for the Name field. Enabling the Description in the addon, & using a blank character in the Description field in the folder Properties, will both enable the tooltip on the folder, and also show the Name along with the (blank) Description. But then the tooltip is unnecessarily large and populated with the Description icon packaged in the addon. The icon can be removed with a simple userstyle, but the presence of the blank space in the field still makes the tooltip box taller than it needs to be for displaying just the folder Name.
It would be very wonderful if this addon could include a checkbox for the Name field in its options, so it could be used to enable tooltips on bookmark toolbar folders, and show only the Name in a compact tooltip.
Also, the delay in making the tooltip visible is a bit long, as mentioned by another reviewer, and some ability to shorten that delay would be real nice as well.
This addon is still very useful to provide the folder Name in a tooltip. There appears to be no other addon that will do this other than the latest Multirow, which is quite repulsive because it is now sponsored & requires an optin that injects links & icons into search results, which the sponsors that pay Multirow+ can use for tracking. Multirow+ claims in the reviews that they do not track their users, but make no mention of what their sponsers do, nor do they mention anywhere in their addon download that optin is required to use it. Multirow+ also leaves an optin preference set to True in about:config after installation, even if optin is never selected or agreed to, and the configuration line remains after Multirow+ is uninstalled, which is simply shameful.
Many thanks to Gabriele for providing this tooltip feature for bookmark toolbar folders. It should be default in Firefox already but is not, possibly because of the issue of the tooltip sometimes blocking an icon being placed on the toolbar.