You wrote a clear rule: maximum 10 guests per booking. Your agent books 15 anyway and reports SUCCESS. The rule was ignored, because to an agent a rule written in the prompt is a suggestion, not a limit. It is the problem web apps solved long ago: do not trust the input, check it before the action runs. So check it at the tool layer instead. A small piece of code looks at every tool call before it happens and compares it to your rules. The prompt-only agent lets every violation through, the guarded one stops them. But blocking is only half the answer. Some rules must never bend, like taking payment, so you block hard. Others are just limits, so instead of dead-ending you steer: the guardrail tells the agent what was wrong, and it fixes its own call. Fifteen guests becomes ten, the booking goes through, and the user is told what changed. You'll walk away knowing how to enforce a rule the agent can't talk past, and when to block hard versus steer it to self-correct.

Outline: • The Prompt Engineering Failure • Neurosymbolic Architecture • Live Implementation: Blocking • From Blocking to Steering • Production Patterns and Q&A