Create a file called specs.empty in home/bob/ansible on the local machine as follows:
HOST=
MEMORY=
BIOS=
VDA_DISK_SIZE=
VDB_DISK_SIZE=
Create the playbook /home/bob/ansible/specs.yml which copies specs.empty to all remote nodes' path /root/specs.txt. Using the specs.yml playbook then edit specs.txt on the remote machines to reflect the appropriate ansible facts.