You can manually pull this (and any other Hyperledger Fabric image) image from DockerHub. There was a period when the fabric-tools image was not included in the helper script download-dockerimages.sh.
docker pull hyperledger/fabric-tools:x86_64-1.0.0-beta
docker tag hyperledger/fabric-tools:x86_64-1.0.0-beta hyperledger/fabric-tools
Note that it might be worth reviewing the set of published tags on DockerHub to be sure you are getting the latest.
https://hub.docker.com/u/hyperledger/