Hi,
I'm not certain what AGZ format means, but if you are referring to an archive file that was created with mongodump using gzip compression you should be able to use a command line similar to:
mongorestore --gzip --archive=data.agz
If you created your backup file with a tool other than mongodump, please provide more information on the tool, version, and command line options used.
Regards,
Stennie