I have successfully created a tag and category for VM using vSphere web client.
When i try see the same using MOB, the value field for tag is empty.
Looked under Managed Object Type: ManagedObjectReference:VirtualMachine
Did i miss any step where i need to assign any privileges or do i need to look for it elsewhere ?
I am able to see values for other fields of the VM.
MOB is client for all vSphere SOAP based APIs. Tags are not part of these vSphere APIs. As part of vSphere 6.5, VMware released REST APIs as well and tag APIs are included there.
Here is REST API getting started tutorial: http://vthinkbeyondvm.com/getting-started-with-vcenter-server-rest-apis-using-python/