<script type="text/javascript" src="popper.js-master/packages/tooltip/tests/functional/tooltip.js"></script>

eventRender: function(info) {
       var tooltip = new Tooltip(info.el, {
        title: info.event.extendedProps.description,
        placement: 'top',
        trigger: 'hover',
        container: 'body'
      });
    },