Agentic Commerce Glossary

The fast-moving vocabulary of agentic commerce, defined in plain language. Where a term has its own reference page, the entry links to it. Suggest a term or a correction and it will be added.

A

A2A (Agent-to-Agent). An open protocol for agents to communicate and delegate tasks to one another. Created at Google, donated to the Linux Foundation in 2025, at v1.0 since March 2026, and a hosted project of the Agentic AI Foundation since 17 August 2026. It is the coordination layer some payment work builds on, for example the x402 extension for A2A. See A2A explained.

ACE (Agentic Commerce Experiences). American Express’s agentic commerce developer kit, published 14 April 2026. It covers agent registration, account enablement, intent intelligence, payment credentials, and cart context. Amex states that account enablement, intent intelligence, and payment credentials are available and that agent registration and cart context are still under development.

ACP (Agentic Commerce Protocol). Open standard for agent-to-merchant checkout, launched in September 2025; latest stable specification 2026-04-17, covering cart, feed, orders, authentication, and MCP. Its README describes OpenAI and Stripe as founding maintainers, while MAINTAINERS.md lists OpenAI, Stripe, and Meta as lead maintainers. Licensed Apache 2.0. See ACP explained.

Agent. Software that can take actions on a user’s behalf, including searching for and purchasing products. In commerce, the “shopper” may now be an agent rather than a person.

Agent Pay. Mastercard’s agentic payments program, announced April 2025. It uses Mastercard Agentic Tokens, built on the same tokenization behind contactless and Mastercard Payment Passkeys, and requires agents to be registered and verified before they can pay.

Agent Pay for Machines (AP4M). Mastercard’s extension of Agent Pay to machine-to-machine payments, introduced 10 June 2026. It targets high-frequency, low-value transactions between agents and services, with agent credentialing, programmatically enforced spending limits, and settlement across cards, accounts, and stablecoins.

Agentic AI Foundation (AAIF). A directed fund under the Linux Foundation, announced 9 December 2025, created as a neutral home for agent interoperability projects. It holds MCP, Block’s goose, OpenAI’s AGENTS.md, agentgateway, and, since 17 August 2026, A2A. It is where both MCP and A2A governance now sit.

Agentic commerce. Commerce conducted by AI agents acting for a user: discovery, selection, authorization, and payment with limited human input. See What Is Agentic Commerce?.

AI-Ready Cards. Visa’s term, under its Intelligent Commerce program, for card credentials tokenized for agent use, so a chosen agent can be authorized to transact within limits the consumer sets.

AP2 (Agent Payments Protocol). Google-led standard for proving a user authorized a purchase, built around signed mandates (originally Intent, Cart, and Payment; now a Checkout Mandate and a Payment Mandate). Donated to the FIDO Alliance on 28 April 2026. Still at v0.2 and described as pre-production. See AP2 explained.

C

Cart Mandate. In AP2’s original (v0.1) model, the signed record of the exact cart the agent assembled for the user to approve.

Checkout Mandate. In AP2’s revised (v0.2) model, one of two credential types, covering the authorization of a finalized checkout. It replaces the earlier Intent plus Cart split with open (pre-cart constraints) and closed (authorization) stages.

Commerce / checkout (layer). The stack layer where an agent browses, builds a cart, and completes a purchase with a merchant. ACP and UCP are the standards here. See the four layers.

D

Delegated payment. A pattern where the buyer authorizes a payment that an agent then presents to the merchant on their behalf, without the agent holding the raw payment credentials. ACP specifies a delegated payment flow; AP2 provides the authorization proof behind it.

Delegated authority. The general principle that an agent acts within authority a user granted, bounded by constraints such as budget, merchant, or time. Mandates and tokens are the mechanisms that make delegated authority verifiable.

Discovery (layer). The stack layer where an agent finds a merchant’s products and the tools it can call. MCP is the standard here. See the four layers.

F

Facilitator. In x402, the service that verifies and settles a stablecoin payment on-chain on behalf of the merchant, so the merchant does not have to operate blockchain infrastructure directly.

FIDO Alliance. The industry body for authentication standards (including passkeys). Google donated AP2 to FIDO on 28 April 2026, where it advances through a Payments working group chaired by Mastercard and Visa and a new Agentic Authentication group.

H

Human-present / human-not-present. AP2 terms distinguishing a purchase a user is actively approving in the moment from one an agent completes later within pre-authorized limits. The distinction shapes how authorization is signaled to the merchant and network.

I

Instant Checkout. OpenAI’s in-chat buying experience in ChatGPT, launched September 2025 on ACP with US Etsy sellers live from day one. In March 2026 OpenAI said Instant Checkout was moving to Apps, with the Agentic Commerce Protocol serving as the infrastructure, shifting the pattern toward discovery in the assistant and checkout on the merchant’s own site.

Intelligent Commerce. Visa’s program, announced April 2025, that opens its network to AI agents through AI-Ready Cards and, from April 2026, an “Intelligent Commerce Connect” on-ramp that works across multiple agent protocols.

Intent Mandate. In AP2’s original (v0.1) model, the signed record of what the user asked for, including constraints like budget.

M

LCP (Legal Context Protocol). Open standard launched 24 June 2026, co-stewarded by Integra Ledger and the American Arbitration Association-International Centre for Dispute Resolution, for publishing the legal terms behind an agent transaction at /.well-known/legal-context.json, optionally with a hash proving what those terms said and a requirement that the counterparty sign acceptance. It addresses the recourse layer that the payment and checkout protocols leave out of scope. Early: the v1.0 specification is a draft for community review and no protocol steward has adopted it. See LCP explained.

Mandate. A cryptographically signed, tamper-evident statement of authorization, expressed as a verifiable credential, that an agent can present as proof of consent. Mandates are the core trust primitive in AP2.

MCP (Model Context Protocol). Created by Anthropic as the standard for how agents discover and call tools and data, and contributed to the Agentic AI Foundation under the Linux Foundation in December 2025. Revisions are date-versioned; 2026-07-28 is the current stable revision and made the protocol stateless. In commerce it acts as the discovery layer. See MCP explained.

MCP extensions. Optional MCP capabilities that version independently of the specification, formalized in the 2026-07-28 revision with reverse-DNS identifiers and a negotiated capability map. Two are official: MCP Apps, which lets a server ship an interactive HTML interface that the host renders in a sandboxed iframe, and Tasks, which handles long-running work and moved out of the core specification into an extension.

Merchant of record. The entity legally responsible for selling to the customer, handling payment, tax, refunds, and chargebacks. In ACP the merchant stays the merchant of record, so the agent surface does not take over the sale.

MPP (Machine Payments Protocol). Open standard co-authored by Stripe and Tempo, launched March 2026, for agents to pay services programmatically. A settlement-layer protocol for machine-to-machine microtransactions and recurring payments, settling in stablecoins as well as the cards, wallets, and other methods Shared Payment Tokens carry. Built on HTTP 402, like x402, and specified as an HTTP authentication scheme submitted to the IETF as an individual Internet-Draft. See MPP explained.

P

Passkey. A FIDO-based, phishing-resistant credential tied to a user’s device, used to authenticate without a password. Mastercard’s Payment Passkeys apply the idea to confirm a user behind an agent-initiated payment.

Payment authorization (layer). The stack layer where the agent proves a real user approved a specific purchase, and where liability is settled. AP2 is the standard here. See the four layers.

Payment Mandate. In AP2, the signed record of what will actually be charged, shared with the payment network and issuer to signal agent involvement and that the user consented.

Product feed. The structured file or API through which a merchant publishes its catalog: identifiers, titles, prices, availability, images, and variants. It is what an agent reads instead of a product page. Each standard defines its own schema (ACP publishes a product feed specification; UCP defines a Catalog capability; Google Merchant Center has its own product data specification), but they ask for substantially the same information. See how to prepare your product catalog.

PSP (payment service provider). A company that processes payments for merchants (for example Stripe). In agentic checkout, the PSP often issues the payment token the agent passes to the merchant.

S

Settlement (layer). The stack layer where money actually moves, across card rails and machine-native options like x402 and MPP. See the four layers.

Shared Payment Token. In ACP, a single-use payment credential issued by the payment service provider and scoped to one specific merchant and one specific cart total. The agent passes it to the merchant to charge, and never sees the buyer’s raw card details. Also reused by MPP for its fiat settlement path, covering cards, wallets, and the other methods the token carries.

Stablecoin. A cryptocurrency designed to hold a steady value against a reference such as the US dollar. Stablecoins (for example USDC) are the settlement medium for machine-native payment approaches like x402 and, optionally, MPP.

Streamable HTTP. MCP’s HTTP transport: a server exposes a single endpoint that accepts JSON-RPC over POST. From the 2026-07-28 revision it is stateless, so the initialize handshake and the Mcp-Session-Id header are gone, every request carries Mcp-Method and (for tool, resource, and prompt calls) Mcp-Name headers so gateways can route without reading the body, and list results carry a cache lifetime. The older HTTP plus Server-Sent Events transport is deprecated. It underpins remote MCP servers. See how to build a remote MCP server.

T

Tempo. The blockchain, incubated by Stripe with Paradigm, that MPP currently settles on, though MPP is designed to work across multiple rails.

Tokenization. Replacing sensitive payment details with a token, so an agent can transact without handling raw card numbers. The shared foundation under most network agent-payment products.

Trusted Agent Protocol. A Visa-led open framework, introduced October 2025, to help merchants distinguish legitimate AI agents from malicious bots when an agent arrives at a storefront.

U

UCP (Universal Commerce Protocol). Google’s standard, co-developed with Shopify, for the broader shopping journey from discovery through checkout to post-purchase. Launched January 2026; current specification revision v2026-08-25, which reorganized the specification into Common, Shopping, and Payment groups, moved payment constructs into the cross-vertical common layer, and added EMV 3-D Secure payment authentication and a Location capability. Its capabilities include Checkout, Cart, Catalog, Order, and Identity Linking over REST, MCP, and A2A transports. Governed by a Governance Council over per-domain Tech Councils for Shopping, Food, and Lodging. The main rival to ACP at the commerce layer. See UCP explained.

Universal cart. The idea of a single cart an agent can fill across multiple merchants. Google announced a product of that name at Google I/O in May 2026 and expanded it at Google Marketing Live on 20 May 2026; as of that announcement the cross-retailer checkout features were described as coming soon rather than generally available.

V

Verifiable credential. A W3C standard for a tamper-evident, cryptographically signed digital claim. AP2 mandates are expressed as verifiable credentials, which is what lets a merchant or network check consent without trusting the agent.

X

x402. A settlement protocol, created by Coinbase, reviving the HTTP 402 Payment Required status for machine-native, often stablecoin, payments. Coinbase’s contribution of the protocol completed with the operational launch of the x402 Foundation under the Linux Foundation on 14 July 2026, with 40 member organizations. Sits alongside MPP at the settlement layer.