diff --git src/wp-includes/class-wp-editor.php src/wp-includes/class-wp-editor.php
index a6504d4..ee877a3 100644
--- src/wp-includes/class-wp-editor.php
+++ src/wp-includes/class-wp-editor.php
@@ -261,7 +261,9 @@ final class _WP_Editors {
 		 *
 		 * @since 2.1.0
 		 *
-		 * @param string $content Default editor content.
+		 * @param string $content        Default editor content.
+		 * @param string $default_editor The default editor for the current user.
+		 *                               Either 'html' or 'tinymce'.
 		 */
 		$content = apply_filters( 'the_editor_content', $content, $default_editor );
 
diff --git src/wp-includes/formatting.php src/wp-includes/formatting.php
index b9383f5..91690d8 100644
--- src/wp-includes/formatting.php
+++ src/wp-includes/formatting.php
@@ -3268,7 +3268,11 @@ function ent2ncr( $text ) {
  *
  * @since 4.3.0
  *
- * @param string $text The text to be formatted.
+ * @see _WP_Editors::editor()
+ *
+ * @param string $text           The text to be formatted.
+ * @param string $default_editor The default editor for the current user.
+ *                               It is usually either 'html' or 'tinymce'.
  * @return string The formatted text after filter is applied.
  */
 function format_for_editor( $text, $default_editor = null ) {
@@ -3281,7 +3285,9 @@ function format_for_editor( $text, $default_editor = null ) {
 	 *
 	 * @since 4.3.0
 	 *
-	 * @param string $text The formatted text.
+	 * @param string $text           The formatted text.
+	 * @param string $default_editor The default editor for the current user.
+	 *                               It is usually either 'html' or 'tinymce'.
 	 */
 	return apply_filters( 'format_for_editor', $text, $default_editor );
 }