What would be nice, especially for automated SMS services...
if you could include suggested response metadata.
This would be useful for say apple iwatch or android wear, in
that you can define recommended responses that the user
"Are you going to the appointment
tomorrow? Yes or No?",
the metadata would includes these suggested messages ["Yes",
You could also add validation logic, e.g. pop a warning if you
input incorrect data.
Heck if you want to be smart about this, you could even
an entire "response" tree, which would increase responsiveness
of common questions/commands.
But ultimately, it would allow you to reply quicker from your
phone or watch.