The best way you can possibly make sure to address critical business effectively and directly with your colleagues or customers is to speak as closely and directly as you can to your audience.
If you can’t be in person then divert to video. If video isn’t available go by phone. If phone isn’t available…then doing it any other way risks losing the intent or tone of your message. And chances are you lose the urgency and timing here as well.
Non-critical items or the coordination to get together for critical items are appropriate in email, chats or text, but keep it short and to the point.
If you have no choice but to use text based then please consider the balance of enough vs. too much. And, please, no repeat messages or passive aggressive jabs to elicit reply.
And as always – issues, emergencies, or personnel problems should always and only be by phone as soon as possible, with a message describing your issue. Trying to solve it any other way will generally slow you down on these and will make it worse.