xbackup and xrestore both write progress messages to their standard output. The amount of information can be influenced by the optional parameters -q and -v, but cannot be fully suppressed.
Any archiver tool is called with the same standard input, standard output, and standard error as xbackup or xrestore, so any messages are included in the protocol.
If xrestore is called for a specific archiver tool (e.g. ADSM, FNET, NSR or OMNI), it writes a numbered list of available saves to standard output and then prompts the user to enter a selection which is a number read from standard input.