Now assuming there is no telepathy, he wouldn't use the tell command. He would just as you say ride on to meet the king. Most role-playing games recognize at least two sets of commands. One set is used for interacting with the world (sometimes known as VR or IC commands) and the other set is for not interacting with the world (know as non-VR or OOC commands) Building, coding, note writing, maintenance, OOC communications are non-VR commands.

If you have telepathy or cell phones or whatever in your world then tell is a IC command. If not then tell is an OOC command.

Many role-playing muds mark this distinction in command set either modally or via special characters. Mush and MOOs have the tradition of using an @ in front of the non-VR command. Some cores allow one to switch modes between VR and non-VR such that the @ sign isn't necessary (or to use a different prefix) or some commands only appear in non-VR mode, edit mode, programming mode, building mode, etc.

For example:
VR commands - say sleep whisper
non-VR commands - @score @who @quit

Whoops - forgot to define VR it stands for virtual reality.