WordPress at a glance
filter is not described

wp_count_comments filter-hook . WP 2.7.0

Filters the comments count for a given post.

Usage

add_filter( 'wp_count_comments', 'filter_function_name_3357', 10, 2 );
function filter_function_name_3357( $count, $post_id ){
	// filter...

	return $count;
}
$count(array)
An empty array.
$post_id(int)
The post ID.

Where the hook is called

wp_count_comments()
wp-includes/comment.php 1255
$filtered = apply_filters( 'wp_count_comments', array(), $post_id );

Where the hook is used (in WP core)

Does not used.