I am having designer access on the database, I want to modify ACL programmatically through agent signed by my ID, I will be able to modify the same

In Lotus Notes/Domino, having Designer access does not grant automatic ability to modify ACLs programmatically through agents. ACL modification requires specific rights and is not permitted through agents even when signed by the designer ID, as this would bypass security controls. This is a security restriction, not a capability limitation.