diff --git a/packages/google-cloud-monitoring/google/cloud/monitoring/gapic_version.py b/packages/google-cloud-monitoring/google/cloud/monitoring/gapic_version.py
index b501783accc6..558c8aab67c5 100644
--- a/packages/google-cloud-monitoring/google/cloud/monitoring/gapic_version.py
+++ b/packages/google-cloud-monitoring/google/cloud/monitoring/gapic_version.py
@@ -13,4 +13,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-__version__ = "2.25.0"  # {x-release-please-version}
+__version__ = "0.0.0"  # {x-release-please-version}
diff --git a/packages/google-cloud-monitoring/google/cloud/monitoring_v3/gapic_version.py b/packages/google-cloud-monitoring/google/cloud/monitoring_v3/gapic_version.py
index b501783accc6..558c8aab67c5 100644
--- a/packages/google-cloud-monitoring/google/cloud/monitoring_v3/gapic_version.py
+++ b/packages/google-cloud-monitoring/google/cloud/monitoring_v3/gapic_version.py
@@ -13,4 +13,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-__version__ = "2.25.0"  # {x-release-please-version}
+__version__ = "0.0.0"  # {x-release-please-version}
diff --git a/packages/google-cloud-monitoring/google/cloud/monitoring_v3/types/metric_service.py b/packages/google-cloud-monitoring/google/cloud/monitoring_v3/types/metric_service.py
index 9e04114b99a5..1bf2317565c3 100644
--- a/packages/google-cloud-monitoring/google/cloud/monitoring_v3/types/metric_service.py
+++ b/packages/google-cloud-monitoring/google/cloud/monitoring_v3/types/metric_service.py
@@ -186,6 +186,24 @@ class ListMetricDescriptorsRequest(proto.Message):
             the ``nextPageToken`` value returned by a previous call to
             this method. Using this field causes the method to return
             additional results from the previous method call.
+        active_only (bool):
+            Optional. If true, only metrics and monitored
+            resource types that have recent data (within
+            roughly 25 hours) will be included in the
+            response.
+             - If a metric descriptor enumerates monitored
+              resource types, only the    monitored resource
+              types for which the metric type has recent
+              data will    be included in the returned
+              metric descriptor, and if none of them have
+              recent data, the metric descriptor will not be
+              returned.
+             - If a metric descriptor does not enumerate the
+              compatible monitored    resource types, it
+              will be returned only if the metric type has
+              recent    data for some monitored resource
+              type. The returned descriptor will not
+              enumerate any monitored resource types.
     """
 
     name: str = proto.Field(
@@ -204,6 +222,10 @@ class ListMetricDescriptorsRequest(proto.Message):
         proto.STRING,
         number=4,
     )
+    active_only: bool = proto.Field(
+        proto.BOOL,
+        number=6,
+    )
 
 
 class ListMetricDescriptorsResponse(proto.Message):
diff --git a/packages/google-cloud-monitoring/samples/generated_samples/snippet_metadata_google.monitoring.v3.json b/packages/google-cloud-monitoring/samples/generated_samples/snippet_metadata_google.monitoring.v3.json
index 8ee408e50639..48dfeb270e77 100644
--- a/packages/google-cloud-monitoring/samples/generated_samples/snippet_metadata_google.monitoring.v3.json
+++ b/packages/google-cloud-monitoring/samples/generated_samples/snippet_metadata_google.monitoring.v3.json
@@ -8,7 +8,7 @@
     ],
     "language": "PYTHON",
     "name": "google-cloud-monitoring",
-    "version": "2.25.0"
+    "version": "0.1.0"
   },
   "snippets": [
     {
diff --git a/packages/google-cloud-monitoring/scripts/fixup_monitoring_v3_keywords.py b/packages/google-cloud-monitoring/scripts/fixup_monitoring_v3_keywords.py
index 335afe7dfed2..9828868a82d0 100644
--- a/packages/google-cloud-monitoring/scripts/fixup_monitoring_v3_keywords.py
+++ b/packages/google-cloud-monitoring/scripts/fixup_monitoring_v3_keywords.py
@@ -70,7 +70,7 @@ class monitoringCallTransformer(cst.CSTTransformer):
         'list_alert_policies': ('name', 'filter', 'order_by', 'page_size', 'page_token', ),
         'list_group_members': ('name', 'page_size', 'page_token', 'filter', 'interval', ),
         'list_groups': ('name', 'children_of_group', 'ancestors_of_group', 'descendants_of_group', 'page_size', 'page_token', ),
-        'list_metric_descriptors': ('name', 'filter', 'page_size', 'page_token', ),
+        'list_metric_descriptors': ('name', 'filter', 'page_size', 'page_token', 'active_only', ),
         'list_monitored_resource_descriptors': ('name', 'filter', 'page_size', 'page_token', ),
         'list_notification_channel_descriptors': ('name', 'page_size', 'page_token', ),
         'list_notification_channels': ('name', 'filter', 'order_by', 'page_size', 'page_token', ),