Richard Duffy finished with aplomb to give the Grecians a seventh-minute lead and Daniel Nardiello worked a clever free-kick with David Noble to fire inside the post in the 77th minute.
Nardiello saw his 80th-minute penalty saved by Walsall goalkeeper Jimmy Walker after John O'Flynn had been fouled in the box by Aaron Lescott and Walsall pulled a goal back five minutes from time when Julian Gray scrambled home a late consolation.
Tisdale said: "I'm happy with three points. Am I happy with three points. We made really heavy work of it.
"We made a great start and it all sort of finished on that. We've got three points and haven't played well, but there've been times where we've played a lot better this season and not got the points.
"We played far better against Brighton and came away with nothing, so maybe it sort of evens itself out a little. I'd like us to have played better and I think we could have played better, but we've got the points."