Avoid caching for anonymous user, on a specified path

Hi I am writing a very simple module to trigger the execution of a function when I access a link:

my code is:

/*
 * Implementation of hook_menu()
 *
 */

function agenda_menu() {
  $items = array();
    $items[] = array(
      'path' => 'agenda/send',
      'callback' => 'agenda_sendsms',
      'type' => MENU_CALLBACK,
      'access' => user_access('send sms'),
    );
  return $items;
}

function agenda_sendsms() {
  $time = mktime();
  print date('c',$time);

}

This is just for test purpose. It works and if I point the browser to that link, the module prints the date.
My problem is that if I access the link a few seconds later, I obtain the same timestamp, as if it is caching the page.
I do not want that drupal caches for this link, neither for anonymous users.

Is there a way to disable caching for just this path?

Thank you