I think It may be easier to have a small array of commands instead of a text box where you write stuff. It's more easy to deploy. You could have a small array of options with labels that gives the hint description of what the option does. Like point and click graphic adventures used to do, but smaller and better. For example, 4 possible action. That for when talking to characters.
If talking about how to move the MC through the world to walk from a room to the other, well, the classic 'doing click on doors' is intuitive enough. you can made the door glow a bit to and to indicate it's interactable and the hint appear in a corner. Same with interact with objects like keys or torches. Basically the most direct and simple (for the player) the better. Unless you were asking for something else and I just got confused. XD