Currently an agent can create a JIRA Service Desk issue within JIRA without a request type specified. You can specify the request type on the view issue screen but not the create issue screen. You can specify the issue type but it will not fill out the request type according to issue type>request match. It will produce a "No Match" on the view issue screen after the issue is created even though the issue type is configured for the request type. This is because one issue type can map to several request types so this can't be done automatically.
Since you cannot specify the request type from create issue view within JIRA. It leaves a possibility that a customer may not be updated if an agent creates an issue from within JIRA.
Since issues should be created via the customer issues should be created via the customer portal by design. Agents should be directed to a JIRA Service Desk Create issue screen where the request type can be specified via either the customer portal, a modified create issue screen, or request type appears on the create issue screen if project type = Service Desk is specified.