This is still generally a good rule when building with agents, the models are capable of many behaviors. The key is to simply set some bounds on what their "job" is so that most of their finite attention can be spent organizing around the what that role is expected to do.

It certainly is less important as the models get better at meta planning, but this approach is still very useful.

Often all you need to do is define a set of beliefs and values for the role and it will operate much better than rules or guidance.