When creating a layer package for a single layer (i.e. not packing a group layer), it is expect that the item description information of the data source is read and used to provide default values for the item information card for the layer package's contents. Supposing the Item Description of the data source has Summary and Tags, it is expected that those be used for the layer package by default (so they would appear in the ArcGIS Online upload dialog box allowing editing).