diff --git a/pkg/cloudprovider/providers/azure/azure.go b/pkg/cloudprovider/providers/azure/azure.go
index 437c783d2da..cc03b5d99eb 100644
--- a/pkg/cloudprovider/providers/azure/azure.go
+++ b/pkg/cloudprovider/providers/azure/azure.go
@@ -34,6 +34,7 @@ import (
 const CloudProviderName = "azure"
 
 // Config holds the configuration parsed from the --cloud-config flag
+// All fields are required unless otherwise specified
 type Config struct {
 	// The cloud environment identifier. Takes values from https://github.com/Azure/go-autorest/blob/ec5f4903f77ed9927ac95b19ab8e44ada64c1356/autorest/azure/environments.go#L13
 	Cloud string `json:"cloud" yaml:"cloud"`
@@ -51,9 +52,13 @@ type Config struct {
 	SubnetName string `json:"subnetName" yaml:"subnetName"`
 	// The name of the security group attached to the cluster's subnet
 	SecurityGroupName string `json:"securityGroupName" yaml:"securityGroupName"`
-	// The name of the route table attached to the subnet that the cluster is deployed in
+	// (Optional in 1.6) The name of the route table attached to the subnet that the cluster is deployed in
 	RouteTableName string `json:"routeTableName" yaml:"routeTableName"`
-	// The name of the availability set that should be used as the load balancer backend
+	// (Optional) The name of the availability set that should be used as the load balancer backend
+	// If this is set, the Azure cloudprovider will only add nodes from that availability set to the load
+	// balancer backend pool. If this is not set, and multiple agent pools (availability sets) are used, then
+	// the cloudprovider will try to add all nodes to a single backend pool which is forbidden.
+	// In other words, if you use multiple agent pools (availability sets), you MUST set this field.
 	PrimaryAvailabilitySetName string `json:"primaryAvailabilitySetName" yaml:"primaryAvailabilitySetName"`
 
 	// The ClientID for an AAD application with RBAC access to talk to Azure RM APIs