We often provide notes (e.g. actions on all members, reminders of upcoming related events that were discussed at the meeting) when sending our draft minutes to members. 500 characters is very restrictive!
It would also be helpful to be able to see the text users will receive with the message and where your comment will sit with that when compiling the message - I have sent a test message to myself but having this info shown on the screen would be very helpful.
