One way to do it would be with a character that the user needs to use to separate the fields. Like |
or ;;
. Something the users wont usually type in the messages.
Then you can split the message with that character.
var arguments = myString.split('|');
And then verify if the user gave all the arguments required:
if(arguments && arguments.length == 3){
// keep going
} else {
// warn the user that the syntax is wrong
}
And finally you would need to generate the Embed.
var embed = new Discord.RichEmbed();
embed.setTitle(arguments[0]);
embed.setDescription(arguments[1]);
embed.setColor(arguments[2]);