Ovftool doesn't support your use-case.
You can export a VM from a host to your local directory. ovftool vi://myip/myVM localPath/myVM.ovf
You can also export a VM into another host. ovftool -ds=mydatastore vi://myip/myVM vi://anotherHost/
* For import directly into host can't be managed by VC.
However it does not support export a VM from one host into another host with OVA/OVF format.
The syntax for supportes use-cases are pretty well documented in user guide.