Yes, it is generally recommended to cook pasta before putting it in a slow cooker. Slow cookers are designed to cook ingredients slowly over a long period of time at low temperatures. While they are great for tenderizing meats and slowly infusing flavors into dishes, they are not ideal for cooking raw pasta.
If you were to add uncooked pasta directly to a slow cooker with other ingredients, the pasta would likely become mushy and overcooked while the rest of the ingredients cook. Additionally, the pasta might release too much starch, affecting the overall texture and flavor of the dish.
To incorporate pasta into a slow cooker recipe, it's best to cook it separately according to the package instructions until it's al dente (firm to the bite). Afterward, you can add the cooked pasta to the slow cooker during the last 15 to 30 minutes of cooking, just to warm it through and allow it to absorb some of the flavors from the other ingredients.
By cooking the pasta separately before adding it to the slow cooker, you'll achieve better results and ensure that the pasta maintains a good texture in the finished dish.