That’s the wrong place. Since 1.6 agent version you need to place the plugins inside "C:\ProgramData\checkmk\agent\plugins". Then you should see some information inside the agent output.
Don’t expect too much from this output it is very rudimentary. I had a own extended HyperV monitoring running in my systems. But no time to port it completely to 2.1. My version had nearly the same information level as the ESX checks.