Can you create a view only role for agents?

You can create a custom Role from the Estate plan in which the agent can only add private and public notes to the ticket. However, if your customers have access to the customer account, the public notes can be seen and also if the "Note added to ticket" notification under Admin--> Email notification--> Requester notification has been turned on, the email notification would be sent to the customer if a public note is added to the ticket. The agent will not be able to make any other changes to the ticket.