In order to get back the peering list, one has to pass the provider
shell
mongocli atlas networking peering list --provider GCP


This is odd because a) Atlas already knows and b) why not list all the peering regardless of the provider. We cannot specify filters in many cases already like, 'cluster list' and would have to use jq to filter. We can do the same here is folks really want to filter. In other words, in general, please stick to one design maxium, provide all items in the 'list' or provide a way to filter, but not both.