Facet UCP Shopping MCP Server

Create a pre-checkout cart from catalog line items. A cart is a mutable scratchpad: it moves no money and holds no inventory, so it carries estimated (server-derived) totals and NO payment_handlers. Assemble it, then create_checkout(cart_id) to convert. REQUIRES IDENTITY on a signature-required Terminal.

Read back one of YOUR carts by id: line items and estimated totals. Owner-scoped, so another agent's id returns not_found. REQUIRES IDENTITY on a signature-required Terminal.

Replace a cart's line items (full replacement), re-priced server-side. Owner-scoped. REQUIRES IDENTITY on a signature-required Terminal.

Open a checkout session for one or more catalog line items (or promote a cart with `cart_id`). Returns the session plus server-resolved `payment_handlers` (rail, pay_to, exact amount) to satisfy: the price and pay_to are the MERCHANT's, sealed here, never read from your request. Physical goods REQUIRE a `fulfillment` ship-to (else FULFILLMENT_REQUIRED), sealed at create. REQUIRES IDENTITY on a signature-required Terminal: a Facet KYA as `Authorization: Bearer <kya>`.

Read back one of YOUR checkout sessions by id: status, totals, line items, payment_handlers. Owner-scoped, so another agent's id returns not_found. REQUIRES IDENTITY on a signature-required Terminal.

Return a checkout's CURRENT sealed snapshot. Facet seals price and items at create, so this is a no-op that reports the session plus a note: to change line items, update the cart and start a new checkout with create_checkout(cart_id). Owner-scoped.

Save a product to YOUR wishlist on this merchant for later. Idempotent: saving the same product again updates its note and keeps the original save time. Scoped to your own agent identity. REQUIRES IDENTITY: Facet KYA as `Authorization: Bearer <kya>`.

List YOUR saved items (wishlist) on this merchant, newest first. Scoped to your own agent identity, so you never see another agent's list. REQUIRES IDENTITY: Facet KYA as `Authorization: Bearer <kya>`.

Remove a product from YOUR wishlist on this merchant. Idempotent: removing something not on your list succeeds with removed:false. Scoped to your own agent identity. REQUIRES IDENTITY: Facet KYA as `Authorization: Bearer <kya>`.

Cancel a cart. Idempotent, owner-scoped, and moves no money. REQUIRES IDENTITY plus an Idempotency-Key on a signature-required Terminal.

Cancel a checkout session before completion, releasing its inventory hold. Idempotent, owner-scoped, and moves no money (distinct from an escrow refund). REQUIRES IDENTITY plus an Idempotency-Key on a signature-required Terminal.

Find businesses in the Facet Universal Business Index that an agent can transact with. Returns `featured` (claimed merchants with a live `terminal_url` — point your catalog and checkout calls there) and `results` (the wider directory). Use this first when you do not already know which merchant to talk to. REQUIRES IDENTITY: send a Facet KYA as `Authorization: Bearer <kya>` on the MCP request. A KYA is an ES256 JWT from Facet's default issuer https://issuer.facet.llc (or another issuer this Terminal trusts — see KYA-Issuers in its /.well-known/agents.txt). Calling without one returns 401 with a signup link.

Search products ACROSS every merchant in the Facet network that has opted into cross-merchant discovery. Returns matches each carrying the selling merchant's `terminal_url` (point your catalog and checkout calls there). Filter by free-text `query` (product name + description), exact `category`, and/or `tags` (all must be present); at least one filter is required. Use this when you know WHAT you want but not WHICH merchant sells it. REQUIRES IDENTITY: send a Facet KYA as `Authorization: Bearer <kya>` on the MCP request. A KYA is an ES256 JWT from Facet's default issuer https://issuer.facet.llc (or another issuer this Terminal trusts; see KYA-Issuers in its /.well-known/agents.txt). Calling without one returns 401 with a signup link.

Which settlement rails this merchant actually accepts (e.g. coin/boson-escrow for escrowed funds that release on fulfilment, coin/usdc-base for direct). Call before get_payment_requirements so you pass a rail_id this merchant registers, rather than guessing. No identity required — this is discovery data.

Turn a `quote_token` from get_quote into a seller-signed payment offer to authorize. Returns `requirements` (escrow address, asset, exact atomic amount, network) — sign it LOCALLY with your own wallet (e.g. @bosonprotocol/x402-client handle402 for `coin/boson-escrow`, producing an X-PAYMENT string). Facet never holds your key and cannot sign for you, which is why paying is two steps and not one. The offer binds to the quote_token's sealed landed total and ship-to, so the amount is the merchant's, not one you name. REQUIRES IDENTITY: same Facet KYA as get_quote, and the SAME `aid` — the offer path rejects a quote_token issued to a different agent than the caller.

Search the merchant catalog for products matching a free-text query.

Complete a checkout you created and place the order by submitting the buyer-signed payment credential. This is the MONEY-MOVING leg: funds capture on-chain to the merchant's pay_to (x402) or into escrow (Boson). The amount is re-derived server-side from the reservation, never your request, and the buyer's signature is verified before any capture. A per-buyer refusal (FORBIDDEN, cap-exceeded, FULFILLMENT_REQUIRED) returns as an error result; a missing or invalid identity is a real 401. REQUIRES IDENTITY plus a signed Idempotency-Key on a signature-required Terminal.

Look up one or more products or variants by identifier (batch).

Read back one of YOUR orders on this merchant: status, amount, settlement state. Use the order_id returned when you paid. You can only read orders your own agent identity placed — another agent's order returns FORBIDDEN. REQUIRES IDENTITY: Facet KYA as `Authorization: Bearer <kya>`.

List YOUR order history on this merchant, newest first. Scoped to your own agent identity — you never see another agent's orders. REQUIRES IDENTITY: Facet KYA as `Authorization: Bearer <kya>`.

Request a refund or return on a DELIVERED order you placed on this merchant. Opens a merchant-approved refund ticket (status `requested`); it moves NO money on its own. The merchant reviews and approves it, and only then does the send-back sign from the merchant's OWN wallet (non-custodial). Amount and recipient are NOT inputs: the refund amount is derived and capped server-side, and the recipient is the order's stamped payer, never one you name. Pass `refund_line_items` to refund only part of the order; omit for the whole order. Owner-scoped: another agent's order returns FORBIDDEN. REQUIRES IDENTITY: a Facet KYA as `Authorization: Bearer <kya>` (an ES256 JWT from https://issuer.facet.llc, or another issuer in this Terminal's agents.txt KYA-Issuers). A wallet-bound KYA also authorizes a platform-originated order by its stamped payer.

Get full product detail by product or variant identifier.

Get the real landed cost of a product from this merchant: goods + shipping + tax for a specific destination, plus a signed `quote_token` the payment path binds to. Call this before paying — the token is what makes the price the MERCHANT's, not one you name. Physical products REQUIRE a `fulfillment` ship-to; without one you get FULFILLMENT_REQUIRED. An unserviceable destination returns UNDELIVERABLE (the merchant's own shipping zones, which Facet cannot waive). REQUIRES IDENTITY: send a Facet KYA as `Authorization: Bearer <kya>` (ES256 JWT from https://issuer.facet.llc, or another issuer in this Terminal's agents.txt KYA-Issuers).