Agentic commerce, explained

Protocols and standards

• The UCP manifest at /.well-known/ucp, explained for merchants

  The UCP manifest, which Google’s developer documentation calls the UCP profile, is a JSON file a business hosts at /.well-known/ucp to declare which Universal Commerce Protocol services and capabilities it supports, where their endpoints are, which payment handlers it accepts and the public keys that verify its messages. An agent platform reads it to negotiate what it can do with the store, and Google’s guide says it must be publicly accessible without authentication.

• Mastercard Agent Pay for merchants

  Mastercard Agent Pay is Mastercard’s programme, announced on 29 April 2025, that lets registered and verified AI agents pay with Mastercard Agentic Tokens, which build on the tokenisation already used for contactless and card on file payments. A merchant meets it in two places: at the website, where Mastercard uses Web Bot Auth so an approved agent can be recognised, and at checkout, where the agent pays with a token through a normal card form.

• Visa’s Trusted Agent Protocol for merchants

  The Trusted Agent Protocol is a Visa specification, announced on 14 October 2025 and developed with Cloudflare, that lets an AI agent prove to a store’s website that it is a known agent rather than an anonymous bot. It is built on HTTP Message Signatures and aligned with Web Bot Auth: the agent signs each request, and the merchant or its CDN checks the signature. It can also say whether the shopper already has an account with the store, and carry optional payment details.

• Visa Intelligent Commerce for merchants

  Visa Intelligent Commerce is Visa’s programme for letting AI agents pay with Visa credentials, announced on 30 April 2025. Visa’s developer pages describe four parts: payment tokens specific to agents, cardholder authentication with passkeys, payment instructions that check a purchase matches what the shopper approved, and signals that record that approval. It is built for agent developers and payment providers, so a merchant meets it as a card payment arriving through an ordinary checkout.

• Web Bot Auth for store owners

  Every decision about admitting agents currently rests on a self declared user agent string, which is trivially copied, so a merchant choosing to allow shopping agents is trusting a claim rather than verifying an identity. Web Bot Auth is the standards effort to make that claim cryptographically checkable, which is what would let a store admit agents narrowly rather than lowering its protection.

• Should you run an MCP server for your store?

  An MCP server exposes your store as a set of tools an agent can call, which is genuinely useful in contexts where an agent already has a relationship with you and largely redundant for anonymous shopping traffic, where a public feed and readable pages do the same job with no maintenance and no attack surface.

• Merchant of record questions in agentic checkout

  The merchant of record is whoever is legally selling: responsible for tax, for consumer obligations and for disputes. In agentic checkout that can differ depending on where the purchase completed, and the practical risk is not that the answer is unfavourable but that most merchants have never asked it and will first encounter it during a dispute.

• Cart mandates explained for merchants

  A cart mandate is a record of what a shopper authorised an agent to buy: the items, the quantities and the amount. It exists so a purchase can be checked against the permission that produced it, and its practical consequence for a merchant is that pricing accuracy stops being a presentation question and becomes a settlement one.

• How agent payments actually settle

  How an agent purchase settles follows from where the checkout happened. When the shopper lands on your own checkout, settlement is your ordinary flow with your ordinary provider. When the purchase completes inside a channel, settlement runs through whatever the platform arranged, and the questions worth asking are about timing, fees and who is named on the transaction.

• The Agent Payments Protocol for merchants

  Google published the Agent Payments Protocol on 16 September 2025, saying it was built with more than sixty collaborating organisations. It addresses authorisation rather than discovery: how a merchant can trust that an agent had authority to spend on somebody’s behalf, which is the question that decides whether agent purchases are safe to accept at scale.

• Implementing the Universal Commerce Protocol

  Google announced the Universal Commerce Protocol at NRF on 11 January 2026, built with Shopify, Etsy, Wayfair, Target and Walmart, and said on its company blog that more than twenty further companies had endorsed it. For merchants it arrives through their platform, and the preparation it calls for is the same catalogue work every other agentic channel needs.

• Implementing the Agentic Commerce Protocol

  The Agentic Commerce Protocol was published by OpenAI and Stripe on 29 September 2025 under Apache 2.0. It standardises how an agent, a merchant and a payment provider agree on a purchase, and it is implemented predominantly by platforms and payment providers rather than by individual stores, which means most merchants encounter it as a set of catalogue requirements rather than as an integration.

• How to tell which protocol your platform supports

  The reliable way to find out which agentic commerce protocols apply to your store is to ask your platform rather than to read the specifications, because support is something the platform implements on your behalf. The more useful question is what the platform requires from you in return, since that resolves to catalogue and policy work you can do immediately.

• Do you need to adopt a commerce protocol at all?

  Most merchants do not implement a commerce protocol directly, because the protocols are adopted by platforms and payment providers rather than by individual stores. What matters for a merchant is which protocols their platform supports and whether their own product data is good enough to be worth transacting on, since no protocol compensates for a price that is not published.