Should document error message "No Device matches"

the only result that 'ebf' specifically checks for in the "message" field in a response is the exact string
"No Device matches".  This should be documented.

Also, why is the case weird in this.  IMHO this string should be changed to "No device matches" (no capital 'D' on 'Devices).

Anyway, whatever string is used in the spec, it should be documented in any spec files that can return it.