In a somewhat hacky implementation, we're using the Description field to store meta-data related to credentials, like server location and such. This has worked well when we were using Passphrase as a manual store, but when we wrote a script to automate it and parse the same data from the description field, we realised that it was not accessible.
I do not think that our implementation is a "good" one, but it fulfils our requirements and seeing as the change to the code is very small to include the description field on the credential into the API return, we would like to see it added. :)