There seems to be a regression in PyTango 8.1.2 (possibly earlier) regarding the "description" attribute property. Defining a default using the key "description" in "attr_list" does nothing (i.e. no default seen by Tango), unlike other attribute properties. However, specifying it using the key "doc" does work. As far as I can tell, both styles should work, and there is evidence that "description" has worked before. I have not tried with any older versions.
Confirmed. Will be fixed in next PyTango 8.1.7
Thanks for reporting.