I guess it is a little late but I have done up a simple man page. Can you take a look and see if it clarifies the usage?
https://raw.github.com/psinnott/gntp-send/master/gntp-send.man
NAME gntp-send
- Utility for sending notifications to Growl using UDP or GNTP protocols
SYNOPSIS
gntp-send [-u] [-a APPNAME] [-n NOTIFY] [-s SERVER:PORT] [-p PASSWORD] title message [icon] [url]
DESCRIPTION Sends notification to local or remote Growl application over UDP or TCP network protocols. When the notification is sent over TCP using GNTP http callbacks and both local and remote icons are supported.
OPTIONS
-a
APPLICATION application name, defaults to gntp-send
-n
NOTIFICATION notification name, defaults to gntp-send notify
-s
HOST:PORT, -s HOST host and port to send notification to, host defaults to localhost and the port defaults to the protocol default (tcp: 23053, udp: 9887), you can specify the host only and the port defaults to the protocol default
-p
PASSWORD password, defaults to not attempting authentication
-u
send the notification over UDP, by default the notification is sent over TCP using GNTP
POSITIONAL ARGUMENTS
title
mandatory, title of the notification
message
mandatory, notification message
icon
optional, local file name or url of icon for the notification
url
optional, url to call if the notification is clicked
DIAGNOSTICS Setting the environmental variable GNTP_DEBUG
will cause the TCP traffic to be printed to STDOUT
0
if the notification was delivered to Growl, this does not mean it was accepted
-1
otherwise