timing belt tool? is it really needed?

[M1L3S]

I just did my hg today

Went to set the belt tension, then realized that it was a hell of alot easier with the motor out of the car.

So I used a open ended wrench , got some leverage on the water pump and pushed pulley. But its still too loose for my comfort. It may be fine or may not be I donno, but I dont think I should be able to slide it around on the cam ........

Any tips , tricks or a tool I can use for the day.

I can just re-tighten it right ? Dont have to re-align everthing ( )