I put as much information as I can on my labels. I haven't had anyone else quilt mine yet, but if I did I'd include their info as well, it's an acknowledgement of their work and the label is there to provide all the information for those looking at the quilt now and in the future. One of my daughters did a small doll quilt (she was 11 at the time), when we did the label we put sewn by XX and quilted by XXXX ("mom").
BTW, just so you have an idea how I do mine, here is an example of a label I made for a quilt that I followed someone's pattern on: