Implementation Notes for Building Deny-by-Default Tool Registries

A tool registry that defaults to deny turns every new capability into a deliberate grant, which keeps the permission surface enumerable as tools multiply.

Tool catalogs grow faster than permission reviews. Deny-by-default converts that growth from silent exposure into a queue of explicit decisions.

Registry rules that hold

• New tools register as denied until a grant names their callers.
• Grants bind tool, caller class, and workflow context together.
• Unused grants expire so the registry reflects reality.

Use the AuthGuardian, security docs, and integration guide to keep the tool surface enumerable as capabilities multiply.