THE SAFETY ARCHITECTURE

SCHEMA-LEVEL TOOL GATING A schema is a formal description of the shape of something, such as a tool's name, what inputs it accepts, and what values are allowed. From Part Four you know that the model only knows about the tools the harness describes to it. Schema-level tool gating means controlling safety by controlling what the model can even ask for. If a dangerous tool is simply not described to the model for a given task, the model cannot call it in the normal way. You can also tighten the schema of tools that are available. For example, a file tool might accept only paths inside one folder, or a database tool might accept only read queries. This is stronger than a prompt rule because it does not depend on the model choosing to obey. The harness enforces the limit in code. Different tasks can get different tool sets. A summarization task needs no ability to send email, so the email tool is removed from its list.