1. Create a gauge widget:
1.1. unselect most checkboxes, but leave description selected;
1.2. in the advanced configuration Description field enter

{ITEM.VALUE};
2. send some data to item;
3. save widget and see that {ITEM.VALUE}

has resolved to the item value;
4. send some more data to item;
5. don't manually refresh page, but wait for widget to refresh (default 1 minute);
6. notice that value has not been updated;
7. check the network activity and observe that request has been sent and response is received, but that response does not contain the new description.

Try doing the same in item widget or honeycomb and you will see that it works correctly there. And the response of those widget actually do contain the new description. Sadly gauge widget does not.