One thing first, you don’t need to query vCenter and ESX host. It is ok if you only query the vCenter server and pull all the data from there.
For your problem you can only do a “cmk -D esxhost.domain.com” take the special agent command as shown in the top section and test this manually on the command line.
There are also the option available in the special agent to create a trace file with the complete communication between agent and vCenter/ESX server.