A qasr construction has a restricted item and an exclusive counterpart. “Zayd is only a poet” concerns descriptions attributed to Zayd; “none is in the house except Zayd” concerns who occupies a place.
With fronting, the initial word alone does not always identify the direction. “You alone we worship” plainly restricts worship, but the neutral order “In the house is Zayd” need not deny everyone else's presence.
Syntax, the alternative being challenged, and the discourse situation must be read together.