Guardrails

Controls that constrain what a model can be asked or allowed to output.

Guardrails are the layers around the model: input filters, output checks, allowed-topic scoping, tool permissions, rate limits. They exist because model behaviour is probabilistic and a prompt instruction is not enforcement. Good guardrails live in your code, not only in the system prompt.

In practice: An output filter that blocks the reply if it contains anything resembling a card number.