What Is an Agent Policy Engine (and Why Deny-by-Default)?

An agent policy engine is the component that decides, per proposed action, whether an agent may proceed — allow, deny, or escalate to a human — before the action is taken. It should be deny-by-default: an action is refused unless a rule permits it, so a gap in the policy fails safe rather than open. It is where an organisation’s authority, limits and risk rules become executable rather than aspirational.

Decides

Allow / deny / escalate, per action

Default

Deny — a gap fails safe

Runs

Before the action, not after

Encodes

Authority, limits, risk rules

Policy before signing

The engine sits between an agent’s proposal and its execution: the agent proposes a structured action, the engine evaluates it, and only an allowed action proceeds. Deny-by-default means the interesting question is what you explicitly permit — an unpermitted or unforeseen action is refused, and genuinely uncertain cases escalate to a human rather than resolving themselves.

Questions

Why deny-by-default instead of allow-by-default?

So an unforeseen action fails safe. Allow-by-default means every gap in the rules is an opening; deny-by-default means every gap is a refusal you can then choose to permit.

What happens to actions the policy is unsure about?

They escalate to a human. Escalation is a designed outcome, not a failure.