Author description on author category

How to add author description on author category? There is a lot of plugins to add it on the end of each post but I mean to add description on the category site grouping posts by one author, like example.com/author/john-smith/. For categories there is:
<?php echo category_description( $category_id ); ?> to insert in category.php file but what is the equivalent for authors that could be put in author.php that would take data editable on author’s profile?