Short-lived credentials for agents

What is wrong with an API key in an environment file?

A static API key is a standing credential. It works until someone revokes it. It works whether or not the agent needs it right now.

Agents make this worse than it already was for scripts. They read files, write logs and echo context into prompts. A key that sits in an environment variable can end up in a transcript or a tool output. Once it is there, anyone who reads the transcript holds the key.

Static keys also drift. They get copied to a second agent, then a third. Nobody rotates them because nobody knows what will break.

What counts as short-lived?

A short-lived credential expires on its own, usually within minutes or hours. It is issued when the agent needs it and lapses after. If it leaks, the window for misuse is small.

Short lifetime is only half of it. The credential should also be narrow. It should cover one system and the actions the task needs, not everything the agent might ever do.

The best case is task-scoped access. The credential exists for one job and is tied to that job's context. NewCore describes replacing standing credentials with short-lived, task-scoped access.

How does an agent get a credential without holding a secret?

This is the chicken and egg problem. To ask for a token, the agent must prove who it is. If it proves that with a stored secret, you are back where you started.

There are three common answers.

• Workload identity. The platform the agent runs on vouches for it. Cloud metadata services, Kubernetes service accounts and CI pipeline tokens all work this way.
• SPIFFE. A workload API attests the process and hands it an SVID, a short-lived certificate or JWT. Aembit and Descope both name SPIFFE.
• A broker or gateway. The agent talks to a local proxy that already knows its identity. The proxy attaches a credential to each outgoing call.

Why keep the credential away from the agent entirely?

If the agent never sees the credential, it cannot leak it. Prompt injection cannot trick it into printing a key it does not have.

This pattern goes by several names. Aembit calls it secretless credential exchange and states that agents never hold standing credentials. NewCore states that the agent never holds the tool's own credential. Idira obtains MCP access tokens for agents and manages rotation on their behalf.

The gateway becomes a high-value target, so check where it runs. Aembit's MCP Identity Gateway runs as a customer-hosted VM. Ask each vendor whether the gateway is hosted by them or by you, and what it stores.

What about tokens that do leak?

Short-lived tokens limit damage by time. Sender-constrained tokens limit it by holder. DPoP binds a token to a key the client keeps, so a copied token fails without that key. Mutual TLS binds it to the client certificate.

Descope supports DPoP, mTLS and private_key_jwt. If your agents pass tokens through many hops, sender constraint is worth asking about.

How do short-lived credentials fit with MCP?

MCP authorization builds on OAuth 2.1. An MCP client gets an access token from an authorization server and presents it to the MCP server. Those tokens should be short-lived like any other.

The 2026-07-28 MCP specification changed client registration. Client ID Metadata Documents replaced Dynamic Client Registration. Each MCP client now identifies itself with a URL it controls. That gives the authorization server a way to know who it is issuing tokens to.

What does just-in-time access add?

Short-lived credentials limit how long a grant lasts. Just-in-time access limits when a grant exists at all. The agent holds no permission until a task needs it.

Together they approach zero standing privilege. Idira applies that model to agents. Cyera Identity issues ephemeral identities that are decommissioned when the task ends. SailPoint Entro offers just-in-time access through Agentic Access Administration.

Where do the scored platforms stand?

Our credentials criterion asks one question. Does the agent hold standing secrets, or does it receive short-lived, scoped credentials?

Aembit scores highest, with policy-based just-in-time access and secretless exchange. NewCore, Descope and Cyera Identity follow closely. Astrix Security's Agent Control Plane issues short-lived scoped credentials.

Several platforms reduce standing secrets without describing token issuance. Silverfort removes standing privileges for agents using static API keys. Clutch Security migrates static credentials to short-lived alternatives. Token Security applies intent-based least privilege for the time required. See the full figures in the standings.

How do I migrate without breaking things?

Start with an inventory of static keys used by agents. Discovery tools find them in code, CI/CD, vaults and endpoints.

Then rank them by blast radius. A key with write access to production data comes first. A read-only key to a test system can wait.

Move one agent at a time. Put a broker in front of the tool, switch the agent to use it, and watch for failures. When it holds steady, revoke the old key. Do not leave the old key in place as a fallback. Fallbacks become permanent.

How short is short enough?

There is no single answer. Shorter is safer but means more token requests. For interactive agent sessions, minutes are common. For batch jobs, the length of the job plus a margin works.

The more important rule is that expiry should not depend on anyone remembering. If a credential needs a person to revoke it, it is standing, whatever its configured lifetime.

A checklist for credentials

• No agent stores a static key for a production system.
• Agents authenticate with workload identity, SPIFFE or a broker.
• Tokens are scoped to one system and one task.
• Tokens expire on their own without manual action.
• High-value tokens are sender-constrained with DPoP or mTLS.
• Old keys are revoked once an agent moves, not kept as fallback.

Read our scoring method for how we weigh credentials against the other six criteria.