diff --git a/Batch/metadata/V1/Task.php b/Batch/metadata/V1/Task.php
index c419878122f..b77ddc6e6ba 100644
Binary files a/Batch/metadata/V1/Task.php and b/Batch/metadata/V1/Task.php differ
diff --git a/Batch/src/V1/JobNotification.php b/Batch/src/V1/JobNotification.php
index e66ed27ce64..dc176543ae2 100644
--- a/Batch/src/V1/JobNotification.php
+++ b/Batch/src/V1/JobNotification.php
@@ -17,8 +17,8 @@ class JobNotification extends \Google\Protobuf\Internal\Message
 {
     /**
      * The Pub/Sub topic where notifications like the job state changes
-     * will be published. This topic exist in the same project as the job
-     * and billings will be charged to this project.
+     * will be published. The topic must exist in the same project as
+     * the job and billings will be charged to this project.
      * If not specified, no Pub/Sub messages will be sent.
      * Topic format: `projects/{project}/topics/{topic}`.
      *
@@ -41,8 +41,8 @@ class JobNotification extends \Google\Protobuf\Internal\Message
      *
      *     @type string $pubsub_topic
      *           The Pub/Sub topic where notifications like the job state changes
-     *           will be published. This topic exist in the same project as the job
-     *           and billings will be charged to this project.
+     *           will be published. The topic must exist in the same project as
+     *           the job and billings will be charged to this project.
      *           If not specified, no Pub/Sub messages will be sent.
      *           Topic format: `projects/{project}/topics/{topic}`.
      *     @type \Google\Cloud\Batch\V1\JobNotification\Message $message
@@ -57,8 +57,8 @@ public function __construct($data = NULL) {
 
     /**
      * The Pub/Sub topic where notifications like the job state changes
-     * will be published. This topic exist in the same project as the job
-     * and billings will be charged to this project.
+     * will be published. The topic must exist in the same project as
+     * the job and billings will be charged to this project.
      * If not specified, no Pub/Sub messages will be sent.
      * Topic format: `projects/{project}/topics/{topic}`.
      *
@@ -72,8 +72,8 @@ public function getPubsubTopic()
 
     /**
      * The Pub/Sub topic where notifications like the job state changes
-     * will be published. This topic exist in the same project as the job
-     * and billings will be charged to this project.
+     * will be published. The topic must exist in the same project as
+     * the job and billings will be charged to this project.
      * If not specified, no Pub/Sub messages will be sent.
      * Topic format: `projects/{project}/topics/{topic}`.
      *
diff --git a/Batch/src/V1/JobNotification/Message.php b/Batch/src/V1/JobNotification/Message.php
index f6a8c7e934b..ab16a4e3bc0 100644
--- a/Batch/src/V1/JobNotification/Message.php
+++ b/Batch/src/V1/JobNotification/Message.php
@@ -10,8 +10,12 @@
 
 /**
  * Message details.
- * Describe the attribute that a message should have.
- * Without specified message attributes, no message will be sent by default.
+ * Describe the conditions under which messages will be sent.
+ * If no attribute is defined, no message will be sent by default.
+ * One message should specify either the job or the task level attributes,
+ * but not both. For example,
+ * job level: JOB_STATE_CHANGED and/or a specified new_job_state;
+ * task level: TASK_STATE_CHANGED and/or a specified new_task_state.
  *
  * Generated from protobuf message <code>google.cloud.batch.v1.JobNotification.Message</code>
  */