diff --git a/mmv1/products/monitoring/MetricDescriptor.yaml b/mmv1/products/monitoring/MetricDescriptor.yaml
index b3b8f2c2b431..c871f2fc72ab 100644
--- a/mmv1/products/monitoring/MetricDescriptor.yaml
+++ b/mmv1/products/monitoring/MetricDescriptor.yaml
@@ -74,6 +74,7 @@ properties:
       The set of labels that can be used to describe a specific instance of this
       metric type. In order to delete a label, the entire resource must be
       deleted, then created with the desired labels.
+    immutable: true
     is_set: true
     item_type: !ruby/object:Api::Type::NestedObject
       properties:
diff --git a/mmv1/third_party/terraform/services/monitoring/resource_monitoring_metric_descriptor_test.go b/mmv1/third_party/terraform/services/monitoring/resource_monitoring_metric_descriptor_test.go
index a34cc21f54db..53ad4f17478e 100644
--- a/mmv1/third_party/terraform/services/monitoring/resource_monitoring_metric_descriptor_test.go
+++ b/mmv1/third_party/terraform/services/monitoring/resource_monitoring_metric_descriptor_test.go
@@ -9,8 +9,6 @@ import (
 )
 
 func TestAccMonitoringMetricDescriptor_update(t *testing.T) {
-	// TODO: Fix requires a breaking change https://github.com/hashicorp/terraform-provider-google/issues/12139
-	t.Skip()
 
 	t.Parallel()
 	acctest.VcrTest(t, resource.TestCase{
@@ -19,8 +17,7 @@ func TestAccMonitoringMetricDescriptor_update(t *testing.T) {
 		CheckDestroy:             testAccCheckMonitoringMetricDescriptorDestroyProducer(t),
 		Steps: []resource.TestStep{
 			{
-				Config: testAccMonitoringMetricDescriptor_update("key1", "STRING",
-					"description1", "30s", "30s"),
+				Config: testAccMonitoringMetricDescriptor_update("30s", "30s"),
 			},
 			{
 				ResourceName:            "google_monitoring_metric_descriptor.basic",
@@ -29,8 +26,7 @@ func TestAccMonitoringMetricDescriptor_update(t *testing.T) {
 				ImportStateVerifyIgnore: []string{"metadata", "launch_stage"},
 			},
 			{
-				Config: testAccMonitoringMetricDescriptor_update("key2", "INT64",
-					"description2", "60s", "60s"),
+				Config: testAccMonitoringMetricDescriptor_update("60s", "60s"),
 			},
 			{
 				ResourceName:            "google_monitoring_metric_descriptor.basic",
@@ -42,8 +38,7 @@ func TestAccMonitoringMetricDescriptor_update(t *testing.T) {
 	})
 }
 
-func testAccMonitoringMetricDescriptor_update(key, valueType, description,
-	samplePeriod, ingestDelay string) string {
+func testAccMonitoringMetricDescriptor_update(samplePeriod, ingestDelay string) string {
 	return fmt.Sprintf(`
 resource "google_monitoring_metric_descriptor" "basic" {
 	description = "Daily sales records from all branch stores."
@@ -53,9 +48,9 @@ resource "google_monitoring_metric_descriptor" "basic" {
 	value_type = "DOUBLE"
 	unit = "{USD}"
 	labels {
-		key = "%s"
-		value_type = "%s"
-		description = "%s"
+		key = "key"
+		value_type = "STRING"
+		description = "description"
 	}
 	launch_stage = "BETA"
 	metadata {
@@ -63,6 +58,6 @@ resource "google_monitoring_metric_descriptor" "basic" {
 		ingest_delay = "%s"
 	}
 }
-`, key, valueType, description, samplePeriod, ingestDelay,
+`, samplePeriod, ingestDelay,
 	)
 }