diff --git src/wp-admin/custom-header.php src/wp-admin/custom-header.php
index 5cc64ef7bf..880caddfde 100644
--- src/wp-admin/custom-header.php
+++ src/wp-admin/custom-header.php
@@ -1304,8 +1304,9 @@ wp_nonce_field( 'custom-header-options', '_wpnonce-custom-header-options' ); ?>
 	}
 
 	/**
+	 * Updates the last-used postmeta on a header image attachment after saving a new header image via the customizer.
 	 *
-	 * @param WP_Customize_Manager $wp_customize
+	 * @param WP_Customize_Manager $wp_customize Customize manager.
 	 */
 	public function customize_set_last_used( $wp_customize ) {
 		$data = $wp_customize->get_setting( 'header_image_data' )->post_value();
@@ -1320,8 +1321,9 @@ wp_nonce_field( 'custom-header-options', '_wpnonce-custom-header-options' ); ?>
 	}
 
 	/**
+	 * Gets the details of default header images if defined.
 	 *
-	 * @return array
+	 * @return array Default header images.
 	 */
 	public function get_default_header_images() {
 		$this->process_default_headers();
@@ -1360,8 +1362,9 @@ wp_nonce_field( 'custom-header-options', '_wpnonce-custom-header-options' ); ?>
 	}
 
 	/**
+	 * Gets the previously uploaded header images.
 	 *
-	 * @return array
+	 * @return array Uploaded header images.
 	 */
 	public function get_uploaded_header_images() {
 		$header_images = get_uploaded_header_images();