For incomplete commands - ones missing a required argument, flag, or option - (if you choose that an interactive prompt will not be appropriate) provide a description, example usage and any optional flags or options in stderr. If this is going to be unreasonably long or complicated, provide a link to documentation detailing all of the above.
Example:
~ lxd import
Description:
Import existing containers
This command is mostly used for disaster recovery. It lets you attempt
to recreate all database entries for containers that LXD no longer knows
about.
To do so, you must first mount your container storage at the expected
path inside the storage-pools directory. Once that's in place,
`lxd import` can be called for each individual container.
Usage:
lxd import <container name> [flags]
Flags:
-f, --force Force the import (override existing data or partial restore)
Global Flags:
-d, --debug Show all debug messages
-h, --help Print help
--logfile Path to the log file
--syslog Log to syslog
--trace Log tracing targets
-v, --verbose Show all information messages
--version Print version number