The tar is fine.
If you were going to do rsync, what I typically use is
rsync -aH --stats /mnt/lfs/tools/ /mnt/backup/tools
The use of the "/" at the end of the source and not at the end of the destination is important. I use the "--stats" rather than the "-v", because verbose can spew out way to much stuff if you have a lot being copied. I'm not sure why the "-r" would be needed, since the command I use descends into all the subdirectories.