In a similar situation at the end of Goodfellas (diner scene), Jimmy (DeNiro) is trying to setup a meeting with Henry Hill (Liotta).

In the narrative, Henry Hill says the the mob always gets someone close and trusted to do the setup. This is exactly what Vito told Michael - that Barzini would get someone close and trusted for the setup.

Therefore, I would say Henry Hill, low-level soldier, was just as "smart" as Don Vito. But Caporegime Tessio wasn't as smart as Vito or Henry Hill.