There is no duty to inform here in Missouri. The following is the general recommendation I give my students for handling a traffic stop. Notice that I neither advocate that they arbitrarily inform, or that they arbitrarily do not inform. Only they can make that decision as they deem appropriate at that moment:

If or when you are stopped, you should pull over as far as you can to the side of the road, turn your radio off, turn the vehicle off, place both hands on the steering wheel where the officer can see them, and await instructions from the officer. If it is dark outside, turn your dome light on so the officer can see into the vehicle as he or she approaches. The time to be fidgeting around looking for your license or insurance card is NOT while you are waiting for the officer to approach your vehicle. Once the officer makes contact with you, he or she will then let you know how they want you to proceed. Remember to avoid making statements that could seem potentially threatening like “I HAVE A GUN”, or making a move to reach for a wallet or other papers that happens to be near where you are carrying your firearm. Remember to be courteous and polite. Like you, the police officer just wants to go home safe at the end of the day.