Paying $0.00001 a call: payment sessions for agents

Some services an agent wants to use cost less per call than the transaction that would pay for them. For those, paying call by call does not work, so the agent needs to open a tab: lock a deposit once, pay each call with a signed note, and settle everything in one transaction at the end. That is a payment session, and agents buying through Nevermined can now pay with one. This post is what the Nevermined team built to get there, and what one real run looked like on Tempo mainnet.

Why can't an agent just pay for each call?

In one of our runs, our agent made five calls to QuickNode's JSON-RPC session endpoint on Tempo, at $0.00001 each. The single transaction that closed the session afterwards cost $0.00006 in gas (the close on the Tempo explorer). That one transaction cost more than all five calls together, and six times the price of one call. Settle each call as its own transaction and every call loses money before it starts.

This is the problem the session intent in the Machine Payments Protocol exists for. Its session intent is meant for many paid interactions in a row, and for sub-cent pricing in particular, so that a client avoids one settlement transaction per tiny payment. Some services sell only that way: QuickNode's session endpoint, Conduit's Tempo JSON-RPC and Dune's SQL API offer a session and no per-call price.

How does a payment session work?

A session is a one-way payment channel between the buyer's wallet and the service.

1. On the first call the buyer locks a deposit in an on-chain escrow.
2. Every call after that carries a signed voucher instead of a transaction. Each voucher states the total owed so far, so the service only ever needs the latest one.
3. The service can take at most the highest voucher it holds, and never more than the deposit.
4. When the session closes, one transaction pays the service what the vouchers add up to and returns the rest of the deposit to the buyer.

Tempo runs two kinds of channel. QuickNode and Dune use Tempo's original channel escrow contract. Conduit uses the newer one built into the chain, the TIP-1034 precompile, which Tempo's session documentation describes as the current one. We support both, because the services in the catalog use both.

What did the run on mainnet look like?

These are two of our runs, paid from a crypto wallet on Tempo mainnet in USDC.e.

Each line is read off the chain, not out of our own records: QuickNode open, QuickNode close, Conduit open, Conduit close. Five calls or five hundred, the session costs the same two transactions.

What does the agent have to do differently?

Nothing. The agent calls a service in the AI Services Catalog the way it calls any other. Opening the channel, signing each voucher, topping up the deposit when it runs low and closing the channel are Nevermined's job. After the close, every call is matched against what the escrow actually paid the service, and each payment record is marked settled with the close transaction as its proof.

Three things about the budget a person gives the agent are worth knowing.

• The budget moves by the price of each call, never by the deposit. The deposit is locked, not spent, and it comes back at close.
• The deposit is capped. Nevermined locks the smallest of what the service asks for, $10, and what the budget and the wallet can cover. A call that cannot fit is refused before anything is signed.
• Gas is the service's choice. A service says in its payment request whether it sponsors the gas to open a channel. QuickNode does, and Conduit does not, so the buyer's wallet paid $0.000042 to open that channel. That gas sits outside the budget, which moves only by what the calls cost.

The details, error codes included, are in the MPP sessions documentation.

Can credits pay for a session?

Yes. With a Nevermined subscription, a session call costs its published rate in credits, and Nevermined's treasury holds the channel instead of the buyer's wallet.

To try it, give your agent a budget and point it at QuickNode's session endpoint in the AI Services Catalog.

Sources

All links were checked on 30 October 2026.

• MPP session intent
• Tempo sessions in MPP
• Stripe: Machine Payments Protocol
• TIP-1034
• Nevermined MPP sessions documentation