In order to receive Server Monitoring Resource Usage webhook notifications, you will need to have the following:

Once you’ve got all of that configured, whenever you receive Resource Usage alerts, your Webhook URL will receive JSON format data as well.

Here’s an example of a CPU Usage warning Webhook notification:

{  
   "monitor_id":"ThisWillBeTheMonitorID32CharLong",
   "monitor_name":"Test Monitor Label",
   "timestamp":1499666613,
   "resource_usage":{  
      "resource_type":"cpu",
      "current_usage":"24.60",
      "average_usage":"25.29",
      "average_minutes":"3"
   }
}

Understanding the parameters:
monitor_id – your monitor’s unique ID (can be found in the link of your monitor’s uptime report)
monitor_name – the label of your uptime monitor
timestamp –  is the unix time stamp at which the event occurred
resource_type – describes which resource type this notification is about (can be: cpu, ram, disknetwork_inboundnetwork_outbound)
current_usage – the current usage (percent) for this server monitor (ie: the usage taken the same minute the notification is sent out)
average_usage – the average usage (percent) over average_minutes minutes (based on your resource usage warning configuration)