diff --git a/src/wp-admin/includes/ajax-actions.php b/src/wp-admin/includes/ajax-actions.php
index c3955b6d77cc6..79f291e3cf3bc 100644
--- a/src/wp-admin/includes/ajax-actions.php
+++ b/src/wp-admin/includes/ajax-actions.php
@@ -454,8 +454,8 @@ function wp_ajax_logged_in() {
  * @since 2.7.0
  * @access private
  *
- * @param int $comment_id
- * @param int $delta
+ * @param int $comment_id Comment ID.
+ * @param int $delta      Change in the number of total comments. Default -1.
  */
 function _wp_ajax_delete_comment_response( $comment_id, $delta = -1 ) {
 	$total    = isset( $_POST['_total'] ) ? (int) $_POST['_total'] : 0;
diff --git a/src/wp-admin/includes/class-wp-importer.php b/src/wp-admin/includes/class-wp-importer.php
index 8489919f8a5e2..c9130c53e2999 100644
--- a/src/wp-admin/includes/class-wp-importer.php
+++ b/src/wp-admin/includes/class-wp-importer.php
@@ -289,9 +289,9 @@ public function stop_the_insanity() {
  * Returns value of command line params.
  * Exits when a required param is not set.
  *
- * @param string $param
- * @param bool   $required
- * @return mixed
+ * @param string $param    The parameter name to retrieve.
+ * @param bool   $required Whether the parameter is required. Default false.
+ * @return string|bool|null The parameter value or true if found, null otherwise.
  */
 function get_cli_args( $param, $required = false ) {
 	$args = $_SERVER['argv'];
diff --git a/src/wp-admin/install.php b/src/wp-admin/install.php
index 64cb4104c41ae..8556c31823ec4 100644
--- a/src/wp-admin/install.php
+++ b/src/wp-admin/install.php
@@ -52,7 +52,7 @@
  *
  * @since 2.5.0
  *
- * @param string $body_classes
+ * @param string $body_classes CSS classes to add to the body tag.
  */
 function display_header( $body_classes = '' ) {
 	header( 'Content-Type: text/html; charset=utf-8' );
@@ -85,7 +85,7 @@ function display_header( $body_classes = '' ) {
  *
  * @global wpdb $wpdb WordPress database abstraction object.
  *
- * @param string|null $error
+ * @param string|null $error Error message to display, if any.
  */
 function display_setup_form( $error = null ) {
 	global $wpdb;
diff --git a/src/wp-admin/nav-menus.php b/src/wp-admin/nav-menus.php
index 5b1a48c123ab2..d2e997b04326a 100644
--- a/src/wp-admin/nav-menus.php
+++ b/src/wp-admin/nav-menus.php
@@ -672,12 +672,14 @@
 }
 
 /**
+ * Adds a CSS class to display the max depth of the navigation menu.
+ *
  * @since 3.0.0
  *
- * @global int $_wp_nav_menu_max_depth
+ * @global int $_wp_nav_menu_max_depth Maximum depth of the navigation menu.
  *
- * @param string $classes
- * @return string
+ * @param string $classes Existing CSS classes for the body tag.
+ * @return string Modified CSS classes including the menu max depth class.
  */
 function wp_nav_menu_max_depth( $classes ) {
 	global $_wp_nav_menu_max_depth;
diff --git a/src/wp-admin/update-core.php b/src/wp-admin/update-core.php
index 308f7e661fb3e..b892d7e9f6c85 100644
--- a/src/wp-admin/update-core.php
+++ b/src/wp-admin/update-core.php
@@ -840,7 +840,7 @@ function list_translation_updates() {
  *
  * @global WP_Filesystem_Base $wp_filesystem WordPress filesystem subclass.
  *
- * @param bool $reinstall
+ * @param bool $reinstall Optional. Whether to reinstall WordPress. Default false.
  */
 function do_core_upgrade( $reinstall = false ) {
 	global $wp_filesystem;