What we found running it

5 results

Connecting a provider means finding out what its API really does, which is rarely what the announcement said. Those results are worth more than the connection, so we publish them — including the ones that contradict our own roadmap.

how we grade

Verified by running it

We executed it ourselves and watched what came back. The strongest thing we can say.

Vendor-documented

The vendor's own docs say so and we read the bytes rather than a summary of them.

Asserted, unverified

Someone claims it and we went looking. Recorded because a plausible claim nobody checks is how a roadmap gets built on one.

Every finding carries the date it was checked. These facts move — an API closed to new signups today can reopen — so a grade without a date is not a claim we would stand behind.

MPP — the Machine Payments Protocol

Verified by running it3 August 2026

A paid HTTP request, signed receipt and on-chain reference, in under two minutes from nothing.

141

services in the registry

1,271

paid endpoints

<2 min

nothing to first paid call

The mppx CLI creates an account, funds it from a free testnet faucet with no signup, and pays for a request. A real call to mpp.dev's paid ping returned a signed Payment Receipt carrying an on-chain reference. MPP is not x402: x402 is Coinbase's stablecoin-only rail on Base, while MPP is payment-method agnostic — cards through Stripe, stablecoins through Tempo, Lightning — and adds idempotency keys, request-body binding, receipts and streaming sessions. It is co-authored by Stripe and Tempo and proposed to the IETF. Visa has published a card-native extension, which is the piece that would let an agent pay ordinary merchants without touching crypto.

What it turns on

Mainnet. Testnet is chain 42431 and mainnet 4217, and testnet cannot reach production services — a mismatch is a hard error, not a fallback. Real calls need pathUSD on Tempo mainnet, and our balance is zero. That single gap is what stands between this and live purchases.

mpp.dev

Shopify's catalog will not connect as a normal MCP server

Verified by running it25 July 2026

It works, but only over raw JSON-RPC — a generic MCP client cannot complete its handshake.

Shopify's Global Catalog answers product search directly, first-party rather than scraped. But its handshake expects a UCP profile URL on every call, inside the request arguments, which generic MCP clients do not send. Adding it as an ordinary MCP server fails; calling it as raw JSON-RPC over HTTP works. Worth knowing before you spend a day wiring it up the obvious way.

What it turns on

Discovery only either way. There is no checkout tool on this surface, so the buy still routes through a payment rail you connected.

Off-session card charges behave correctly under replay and 3DS

Verified by running it30 July 2026

Charged with nobody present, replayed safely, and failed in the right way.

In Stripe test mode: a SetupIntent confirmed Link was enabled on the account, an off-session charge succeeded with no one there to approve it, a replayed idempotency key returned the same PaymentIntent rather than a second one, and a card requiring 3DS came back as authentication_required — which is the branch a 402 handler needs to key on. Guards in place: a server-side per-charge ceiling, a required reference used as the idempotency key, ownership checks, and only card and Link ever saved.

What it turns on

Test mode, not production. The rail is built; it has not moved real money.

PayBox holds credentials today, but cannot issue a card yet

Vendor-documented30 July 2026

The card API surface ships; the credential type behind it does not exist yet.

MoonPay's own help centre puts payment card support in Phase 2. A real vault therefore holds wallets and secrets, and can release an approved secret to your agent, but has no card for anyone to charge — the card API is built on our side and has nothing to point at. Separately, wallet signing, swaps and x402 all complete inside an in-chat signing window that only an MCP host can draw, so those belong to an MCP client rather than to a web app. Read from the vendor's own bytes rather than a summary.

MoonPay PayBox FAQ

Amazon is not an MPP integration

Asserted, unverified3 August 2026

A claim we went looking for and could not stand up.

Amazon does not appear on MPP's own overview, is absent from the 141-service registry, and is missing from the Visa and Stripe coverage. An Amazon logo in this context is most likely a general agentic-commerce landscape graphic rather than an MPP integration. Recorded here because a plausible claim that nobody checks is how a roadmap ends up built on one. Amazon checkout does work here — through Purch, on a different rail entirely.