When creating a Windows Performance Counter unit monitor, you might want to include in the alert description four pretty important pieces of information: Performance Object Name, Counter Name, Instance Name, Counter Value. Here are the expression that you need to use in order to include this info in the alert description:

1. Counter Value                      - $Data/Context/Value$
2. Performance Object Name    - $Data/Context/ObjectName$
3. Performance Counter Name  - $Data/Context/CounterName$
4. Performance Instance Name - $Data/Context/InstanceName$