OK, so in my earlier reply to you I had located "pacing" as something happening at the scene/scene transition level, but here you are bringing it back to the word choice in the moment level.
If your two questions (at the end of the first quote, and in the second quote) are accepted as purely rhetorical, then I think you're putting a lot of pressure on the form/content distinction: because the best way to present the invitation to action is via this rather than that choice of words.
I think my feeling is that, while there may be some word choices that are clearly better than others in this respect, (i) there is no optimum, and (ii) crossing the bar to satisfactory is generally straightforward enough that it's not a significant challenge of composition. But I need to think more. And I'll try and see what happens the next time I GM a game!
Couple thoughts. One related to the above, a third unrelated to the above.
1) I agree with both "there is no optimum" and "crossing the bar to satisfactory is generally straightforward enough that its not a significant challenge of composition."
The only daylight remaining is "assuming satisfactory word choice deployed to coherently (with respect to theme, mechanics, pacing) frame situation and invite to action, is it plausible that one arrangement of words (or noises made from mouth, put another way) can move beyond the realm of satisfactory (in terms of provocation)...even if just subtly so?"
I'm going to move a bit sideways here and think about monsters, on the axes of both economy and provocation.
Remember the 4e Night Hag standing between (figuratively at first) Thurgon and the safety of his King in our game?
It has the awesome Dream Haunting (psychic) ability that attacks stunned or unconscious creatures (vs Will), removes the Hag from play and delivers continuous psychic damage until the target is dead or no longer stunned or unconscious.
Then, the Night Hag has Wave of Sleep (Recharge 5, 6) that dazes and renders unconscious on a failed save.
We don't need a giant page of text to tell us about "Night Hag Ecology" to let us know about its place in our games (ripped straight from nightmarish folklore). The way the mechanics work together, what it attacks, what it does...those collection of words (mechanics in this place) and their brevity let us put the puzzle pieces together. And when we do, its visceral (because they're constructed so beautifully).
Then look at Dungeon World's Monster entries. Economic, provocative prose that compels your (the GMs) decision-points in how to integrate the creature as a looming or immediate threat when a danger needs introduced or a player move go awry. Take the Gnoll Tracker (without Tags, Qualities, HP, etc) entry from Ravenous Hordes (that subtype alone doing a good bit of work):
Once they scent your blood, you can’t escape. Not without intervention from the gods, or the duke’s rangers at least. The desert scrub is a dangerous place to go exploring on your own and if you fall and break your leg or eat the wrong cactus, well, you’ll be lucky if you die of thirst before the gnolls find you. They prefer their prey alive, see—cracking bones and the screams of the dying lend a sort of succulence to a meal. Sickening creatures, no? They’ll hunt you, slow and steady, as you die. If you hear laughter in the desert wind, well, best pray Death comes to take you before they do. Instinct: To prey on weakness
Doggedly track prey
Strike at a moment of weakness
2) What do you think about the hierarchy I listed above?
My (1) in the hierarchy would be the deft deployment of the Night Hag or Gnoll Trackers as newly framed antagonism, a looming threat, or an immediate reprisal.