When designing a system prompt for an agent, what is the primary purpose of defining explicit 'constraints' beyond 'goals' and 'persona'?

When designing a system prompt for an agent, 'goals' define what the agent should achieve, specifying its primary objectives or desired outcomes. 'Persona' establishes the agent's identity, tone, and style, dictating how it should present itself and interact. Beyond these, the primary purpose of defining explicit 'constraints' is to impose specific limitations, rules,....