WordPress at a glance
action is not described

add_meta_boxes_comment action-hook . WP 3.0.0

Fires when comment-specific meta boxes are added.

Usage

add_action( 'add_meta_boxes_comment', 'action_function_name_893' );
function action_function_name_893( $comment ){
	// action...
}
$comment(WP_Comment)
Comment object.

Where the hook is called

In file: /wp-admin/edit-form-comment.php
add_meta_boxes_comment
wp-admin/edit-form-comment.php 190
do_action( 'add_meta_boxes_comment', $comment );

Where the hook is used (in WP core)

Does not used.