There is one specific situation in which you use the Add entity (optional) field when you add a user turn as a means to capture a user's answer to a bot question. In that case, you need to select the entity that must be present in your user's utterance for it to match the intent.
Set required entity for intent matching
To select just a required entity:
Step 1: In the 'Add entity (optional)' field, select the entity from the drop down list or create a new one.
Step 2: In the example below, a user utterance will only be matched to the intent 'State.pizza.topping' when it contains an entity value for the entity pizza.topping.
Step 3: In all other cases, the user is sent to no.response.
Set required entity value for intent matching
If you want to make the matching even more precise, you can specify a specific entity value that should be present in the user utterance:
Step 1: Select the Match specific entity value option.
Step 2: Enter the entity value that should be present. In the example below, a user utterance will only be matched to the intent pizza.topping when the specific entity value 'Mushroom' or one of its synonyms is present.
Step 3: In all other cases, the user is sent to no.response