I am using the line tool in Photoshop but my lines keep coming out blurry like this:
Why is this the case?
I'm not sure whether this should actually be just a comment, but the reason you're getting blurred, slightly jagged edges, is because you're using the line tool on a fairly low resolution image and are zoomed in.
Try changing your zoom to 100% and see if the jaggedness remains. If you need more detail, then consider changing the resolution of your image (either change the X/Y pixel count or change the number pixels per unit).
To solve this issue. increase the ppi. pixels per inch.make it to 300 ppi.