The instrument in Renoise 3 has a feature which is well and truly hidden:
It supports comments and tags, both will be saved along with the instrument just fine.
It’s just that we don’t have any way to view or edit those comments or tags - until now!
The tool is simple to use - drag to install the xrnx, then right-click any instrument to view/edit
(the dialog will automatically update as you switch between instruments)
You can enter multiple tags in one go by separating each one with a comma
Edit existing tags by clicking them twice (once selected, hit DEL to remove it quickly)
Edit: the tool download is now on the official tools page: