To add a description
;; Set activeX variables
(setq XAcadObject (vlax-get-acad-object))
(setq XActiveDoc (vla-get-activedocument XAcadObject))
(setq XActiveLayout (vla-get-ActiveLayout XActiveDoc))
(setq XLayersCol (vla-get-layers XActiveDoc))
;; Create layer description
(if(or(= 16.1 (atof(getvar "acadver")))(< 16.1 (atof(getvar "acadver"))))
(progn
(setq VLA-Obj(vla-add XLayersCol Layer))
(vla-Put-Description VLA-Obj "YOUR DESCRIPTION HERE")
)
)