When I use the "Filter" function in Configuration->Hosts (or Templates)->items section, for example if I want all the eth0 traffic items, I write "eth0" in "Description like" field.
Nothing is found, but if I use the same filter in the "key like" field, items are found.
I think the problem is that the description in the item is "Incoming traffic $1", and it's only expanded in visualization, but not during searches