diff --git a/modules/field/field.api.php b/modules/field/field.api.php
index b0fc6a4..50f2647 100644
--- a/modules/field/field.api.php
+++ b/modules/field/field.api.php
@@ -1312,6 +1312,13 @@ function hook_field_attach_load($entity_type, $entities, $age, $options) {
  * This hook is invoked after the field module has performed the operation.
  *
  * See field_attach_validate() for details and arguments.
+ *
+ * @param $entity_type
+ *   The type of $entity; e.g. 'node' or 'user'.
+ * @param $entity
+ *   The entity with fields to validate.
+ * @param array $errors
+ *   An associative array of error keyed by field_name, language and delta.
  */
 function hook_field_attach_validate($entity_type, $entity, &$errors) {
   // @todo Needs function body.