Developer beta

A trusted checkout surface for agents.

Onsell is building on ACP 2026-04-17 over MCP 2025-11-25: structured commerce tools, live server-side pricing and a confirmation boundary before any order is placed.

Endpoint

POST https://your-onsell-host/api/mcp

TransportStateless Streamable HTTP with JSON responses.

AuthenticationBearer token in production; credentials stay out of tool arguments.

Agent commerce standard · Draft 0.1

Adopt the contract in layers.

Platforms advertise the profiles they support instead of making an all-or-nothing compatibility claim. The Onsell beta is the reference implementation for checkout and order semantics; catalog portability remains a draft contract.

01Draft contract

Catalog profile

Discover businesses, locations, offerings, prices, availability, service areas, and supported fulfillment modes.

02Reference beta

Checkout profile

Create, read, update, or cancel a persisted checkout while the provider remains authoritative for every total.

03Reference beta · placement only

Order profile

Bind consent to an exact checkout revision and create a durable Onsell order reference; payment and external handoff are not included.

Tool surface

Five checkout tools. No UI plumbing.

These tools expose persisted checkout operations. Echo-specific presentation and question tools remain internal to the Onsell app.

create_checkout_session

Create a persisted QAR checkout from live Onsell products and options.

write

get_checkout_session

Read the current checkout revision, lines and authoritative totals.

read

update_checkout_session

Replace items or update buyer and fulfillment details, then re-price.

write

complete_checkout_session

Re-price and place only after explicit confirmation of the current revision.

financial

cancel_checkout_session

Cancel a checkout that has not already completed.

destructive

Checkout contract

Create

Send product ids, quantities and selected option ids.

Review

Use the server-resolved QAR total and current revision.

Confirm

Collect the customer’s explicit confirmation outside the model’s assumptions.

Complete

Submit that revision with a fresh idempotency key.

Safety properties

The model never sets the price.

Products, options, merchant status and availability are validated against Onsell’s database.
Every checkout contains products from one merchant and all amounts use integer QAR minor units.
Create, update, complete and cancel mutations require idempotency keys.
Completion safely replays against one internal order idempotency identity.
Payment credential payloads are not stored, logged or passed into the order database.

Protocol status

This is an ACP-oriented developer beta, not a claim of full ACP conformance. Live payment processing, delegated payment and public OAuth client onboarding are not advertised by this surface.

View discovery