I know it's been asked two years ago, but for those who still has this question in 2020 and further: yes, it is possible to add a description.
You need to navigate to tenant mgmt and then to Node Management Addresses > Static Node Management Addresses.
Pick a specific node that you are interested in and along with an IP address for OOB management interface you will be able to add a description, see the screenshot attached. This description will appear under your mgmt0 interface.
