Example of to change the defautl gateway order description to use an itemized list of '{ticket name} x {qty}'

tw_ee_itemized_tickets_description.php

<?php // Please do not include the opening PHP tag if you already have one

add_filter( 'FHEE__EE_Gateway___order_description',
	'tw_ee_itemized_tickets_description', 10, 3
);
function tw_ee_itemized_tickets_description( $desc, $gateway, $payment ) {
	$desc_array = array();
	$txn = $payment->transaction();
	$ticket_line_items = EEH_Line_Item::get_ticket_line_items($txn->total_line_item());
	foreach($ticket_line_items as $ticket_line_item) {
		if( $ticket_line_item instanceof EE_Line_Item) {
			$desc_array[] = $ticket_line_item->name() . ' x ' . $ticket_line_item->quantity();
		}
	}
	if( !empty($desc_array) ) {
		return implode(", ", $desc_array);
	}
	return $desc;
}