Wednesday, June 17, 2026

Hermes agents can now pay for APIs with MPP

Nous Research adds an MPP skill for per-request agent payments

Nous Research has added an MPP payments skill to Hermes. With mpp-agent, a Hermes agent can pay APIs that charge per request, settling each call as it happens instead of relying on a subscription, shared API key, or manual checkout.

The skill is part of a broader set of payments capabilities built with Stripe, and it uses the Machine Payments Protocol for the 402 payment flow.

What MPP does

MPP is an open standard for machine payments. It defines how a client pays for a resource over HTTP. A server responds with 402 Payment Required and a Challenge describing the price, the client submits a Credential, and the server fulfills the request with a Receipt.

The same pattern supports one-time charges, variable usage within a single request, and recurring subscriptions. MPP was co-authored by Tempo and Stripe.

What the skill does

The mpp-agent skill is a client for these flows. It installs on its own, with no changes to Hermes itself:

terminal

$ hermes skills install official/payments/mpp-agent

Once installed, Hermes can pay 402-gated endpoints using the mppx client and a wallet of the user's choosing, including Tempo Wallet. Users who don't need payments don't have new core tools or configuration to manage.

The agent acts, the user sets the spending bound

Nous designed the skill so autonomy doesn't mean losing control of spend. Wallet keys never enter the agent's transcript, logs, or memory. Spend approvals sit outside the agent and can't be bypassed by it. Final amounts are confirmed before any payment goes through.

That split makes machine payments workable in production. The agent decides what to pay for, request by request, within limits the user sets and the agent can't override.

Why an open standard matters

Nous built this without involvement from the MPP team. That's what an open standard is for. Any agent framework, wallet, or API can implement MPP and interoperate with the rest, without asking permission and without locking into a single provider.

The mpp-agent skill supports more than one wallet, and MPP works across payment methods and chains.

Build with MPP

If you're building an agent that needs to pay for things, you can add MPP the same way Nous did. If you run an API, you can price it per request and accept MPP payments directly.