$json = $megaCurl->setRequestUrl("http://a1b1c1.ru/api/addTask?key=$key&post_id=$post&count=$count&interval=1200")->execute();

  if ( $json !== false && isset($json->status) ) {

    if ( $json->status != 'error' ) {

      success...
    } else {

      error...
    }
  }