A measure that closes off a path to harm, without anyone having to read the rule.
What must never happen is secured not by a rule in the text but by a guardrail, for example by never giving Claude access to a service in the first place. Bold type and exclamation marks are not a guardrail. For every guardrail you write down which path it closes, because it does not cover the rest. The sentence in the file stays anyway, because it explains why the guardrail exists.
Example from Module 8
Planning office [example]: No service that can send messages is connected to Claude. Claude delivers the defect notice as text, and only a person can send it, from their own mailbox.
Module 8: “Storing knowledge for good”. In the Werkbank course room, with sign-in.
Related terms
- Hard ruleOne of the few rules where a single breach can do real harm. Everything else is guidance.
- Rules fileA document with the permanent rules of a recurring task, in which every rule appears exactly once and hard rules are kept apart from guidance.
- EncapsulationYou decide what an agent may see and touch, and what it may not.