How Should AI Agents Authenticate?

An AI agent should authenticate with a verifiable credential that names who it acts for and what it was authorised to do — not with a shared, long-lived API key that says nothing about accountability. Authentication proves identity; it must be paired with authorization, which proves what the agent may do. The strongest pattern binds a request to a delegation chain that a service can verify back to an accountable human.

Prove

Which agent, acting for whom

Avoid

Shared, long-lived bearer keys

Pair with

Authorization (what it may do)

Verify

The delegation chain, at use time

Authentication is not authorization

Proving an agent is who it claims does not tell a service what the agent is allowed to do. Authentication answers identity; authorization answers permission. An API key blurs the two and carries no accountability — anyone holding it is indistinguishable. A credential tied to a verifiable delegation chain answers both and names who is responsible.

Questions

Can agents use OAuth?

OAuth-style flows can grant an agent scoped access, which is a step up from a shared key. The key addition for agents is a verifiable chain back to the human who delegated the authority.

Why not just give an agent an API key?

A key authenticates a request but carries no identity or accountability — it cannot say which agent holds it or who authorised it, which is what a counterparty needs to know.