I understand that technically these are not tools, but ingredients.
However, I have come to learn, with lots of practice in the kitchen, that these two ingredients are the key to good food & therefore, to me, they are tools.
You can pretty much season anything properly & have it come out delicious.
When cooking, I use Kosher salt...in particular, Diamond Crystal brand. Kosher salt is flaky & can be crumbled between your fingers over food. Which is why it's stored it in a salt box & not a grinder. It is less salty than table, or sea salt. So, when cooking with it, you need to add a bit more than the others.
Freshly Ground Black Pepper
I have yet to find the perfect pepper grinder. Otherwise, I would link to one. I have a feeling I need to spend a bit to get a great one.
However, pepper is the sister component & it's essential to fantastic tasting food.
If you look at the recipes of many famous cookbook authors, you will see that seasoning generously with salt & freshly ground pepper is a common thread. Try it. I promise it will change the way your food tastes.