Least Privilege: Permission Design and Scoped Credentials

Jerome Saltzer and Michael Schroeder stated this design principle in their paper "The Protection of Information in Computer Systems":

Every program and every user of the system should operate using the least set of privileges necessary to complete the job.

The principle is decades older than language models, and it matters even more for agents than for ordinary programs. With an ordinary program, you can read the code and list what it will do. With an agent, the next action is chosen while the run is in progress, and it may be influenced by a mistake or by text that an attacker wrote