Communication effectiveness is an empirical matter exceeding formal minimum standards.

Evidence

And, while a purely formal theory of communication may derive certain minimum standards of “efficiency” in communication that rational players ought to achieve, it is an empirical question whether players can do better than that. How well one can take a hint and what kinds of hints are most successful are empirical questions of social perception, probably amenable to experimental study. — Thomas C. Schelling, The Strategy of Conflict, 792