My site needs less water, or maybe more? How to observe to tell what it needs?

I’m currently in the process of observing my site and planning it out and i’m not sure if i should install swales to get rid of water, swales to make sure water stays, or to leave it alone.

The soil on my site is moraine clay, and the site has a slight slope (maybe 2-3%).

Normally with clay, many focus on how to reduce water levels due to poor drainage, but with a slope they often install swales to keep the water onsite and allow it to actually penetrate the soil rather than flow away.

How do i tell/test for what my site needs?