The agentic protocol landscape

Last verified: 9 August 2026

Read this first

That's the reason this page exists, and the reason it carries a date at the top. Anything written about agentic protocols has roughly a ninety-day shelf life. We re-verify this table every quarter against primary sources — spec repositories, foundation announcements, and vendor documentation — and we tell you when we last did it.

If you take one thing away: the protocols are consolidating faster than they are competing. The Linux Foundation and the FIDO Alliance now steward most of what matters. That's a good sign for anyone deciding whether to build. It means the odds of your integration work being stranded went down sharply in 2026.

The map

Four layers, and they stack. An agent needs to find you, talk to your systems, agree on a transaction, and settle it. Each layer has its own standard, and they mostly don't overlap.

• Interoperability — how an agent connects to tools and data. MCP.
• Coordination — how agents talk to each other across company boundaries. A2A, AGNTCY.
• Commerce — how an agent discovers products and completes a purchase. UCP, ACP.
• Trust and settlement — how a merchant knows an agent is legitimate, and how money moves. AP2, Visa TAP, Mastercard Agent Pay, x402, MPP.

Plus one that sits outside the stack: the browser layer, where the page itself hands tools to an AI running in the visitor's tab. That's WebMCP, and it's the newest thing here by a wide margin.

Model Context Protocol (MCP)

What it does: Connects an AI agent to your tools and data. If you've built an integration that lets Claude, ChatGPT, or Copilot read from your systems, you almost certainly built it on MCP.

Who controls it: The Agentic AI Foundation, a directed fund under the Linux Foundation. Anthropic created MCP and donated it in December 2025, co-founding AAIF alongside Block and OpenAI. Governance runs through individual maintainers, not company seats — there is no vendor with a controlling stake.

Should you build on it: Yes. This is the most settled standard on this page. But check which spec revision your existing servers target, because the July 2026 release broke things. We go deeper on that in MCP, A2A, and the agent interoperability stack.

Agent2Agent (A2A)

What it does: Lets autonomous agents from different organizations discover each other, negotiate, and hand off work. Where MCP connects an agent to your tools, A2A connects your agent to someone else's agent.

Who controls it: The Linux Foundation, as a standalone project. Google donated it in June 2025 with AWS, Cisco, Microsoft, Salesforce, SAP, and ServiceNow as founding partners.

Should you build on it: Yes, and the reason changed this year. A2A hit version 1.0 in March 2026 — its first stable release. The wait-and-see position that made sense in 2025 doesn't anymore.

Universal Commerce Protocol (UCP)

What it does: Lets an AI agent browse a merchant's catalog, build a cart, and complete a purchase — with the merchant keeping control of pricing, inventory, and the customer relationship.

Who controls it: A Tech Council originally formed by Google, Shopify, Etsy, Target, and Wayfair. In April 2026 it expanded to include Amazon, Meta, Microsoft, Salesforce, and Stripe.

Should you build on it: This is where the commerce layer consolidated. If you sell things and you're picking one commerce standard, pick this one. The full treatment is in Agentic commerce protocols, explained.

Agentic Commerce Protocol (ACP)

What it does: Originally, agent-mediated checkout inside ChatGPT. As of 2026, primarily product discovery — with the merchant running their own checkout.

Who controls it: OpenAI and Stripe as founding maintainers, with Meta on a three-of-seven Technical Steering Committee. No foundation donation. Neutral stewardship is described as a long-term aspiration, not a plan.

Should you build on it: Yes for discovery — being findable inside ChatGPT has obvious value. Be careful about building checkout on it. That's the part OpenAI pulled back.

The payment and trust layer

Four things happened here in 2026, and together they're the biggest structural shift on this page. Each one gets unpacked in Agent payment rails, explained.

AP2 went to the FIDO Alliance. Google donated the Agent Payments Protocol in April 2026. FIDO stood up two working groups: Agentic Authentication (chaired by CVS Health, Google, and OpenAI) and Payments (chaired by Mastercard and Visa). Mastercard contributed its Verifiable Intent work at the same time. FIDO is now the neutral ground where the card networks and the AI labs are in the same room.

Visa's Trusted Agent Protocol launched in October 2025, built on HTTP Message Signatures (RFC 9421) and aligned with Web Bot Auth, developed with Cloudflare. It uses a three-signature model — agent recognition, consumer identity, payment container. Pilots ran through late 2025 and 2026. Visa has not donated TAP to a standards body.

Mastercard Agent Pay launched in April 2025 — earlier than most write-ups suggest — and became usable on ACP in late September 2025. In June 2026 Mastercard added Agent Pay for Machines, aimed at high-frequency machine-to-machine transactions across cards, accounts, and stablecoins.

Machine payments became a category. The x402 Foundation launched under the Linux Foundation in July 2026 with forty member organizations, including Visa, Mastercard, Stripe, AWS, Google, Cloudflare, Coinbase, and Amex. Separately, Stripe and Tempo shipped the Machine Payments Protocol in March 2026. If your roadmap includes agents paying for things autonomously — API calls, compute, data — this is the layer to watch.

The advertising layer

Two competing standards, and anyone telling you there's only one hasn't looked recently.

Ad Context Protocol (AdCP) is stewarded by AgenticAdvertising.org, a 501(c)(6) still completing its formation. Current version 3.1.4 as of July 2026, with 123+ members including Yahoo, PubMatic, Scope3, Samba TV, and LG Ads. The first agent-to-agent media buy with real money ran in October 2025.

AAMP — the IAB Tech Lab's Agentic Advertising Management Protocols — shipped v1.0 in January 2026 and v2.3 in July 2026. It takes the opposite approach: rather than a new protocol, it extends the standards the industry already runs on (OpenRTB, AdCOM, OpenDirect, VAST, Deals API, GPP) with an agentic layer.

They are not aligned. The IAB's published materials don't mention AdCP, MCP, or A2A. If you're planning agentic media buying, this is an unresolved bet, not a settled standard.

The browser layer: WebMCP

What it does: Flips MCP around. Instead of a server exposing tools to a remote agent, the page itself registers tools that an AI running in the visitor's browser can call — using their live session, their cookies, their authenticated state. No API keys, no auth handoff.

Status: Early. It's a Draft Community Group Report from the W3C Web Machine Learning Community Group — not on the standards track and not in a Working Group. Chrome is running an Origin Trial across versions 149 through 156. Microsoft co-authors the spec. WebKit has an open request with logged concerns about privacy, security, and API design. Mozilla has published no position.

Should you build on it: Only if you can absorb churn. The API changed in 2026 — navigator.modelContext was deprecated in Chrome 150 in favor of document.modelContext, and the earlier provideContext() method no longer exists. Anyone who shipped against the old surface has broken tools. That's the shape of this standard right now. We run WebMCP on this site and document exactly what that cost in WebMCP: when your website hands tools to the agent.

AGNTCY

What it does: Infrastructure underneath multi-agent systems — a federated agent directory, identity and verifiable credentials, secure messaging (SLIM), a schema framework (OASF), and observability.

Who controls it: A Linux Foundation project since July 2025. Formative members: Cisco, Dell, Google Cloud, Oracle, and Red Hat. It is not part of the Agentic AI Foundation.

Should you build on it: Watch it. The code is actively maintained, and A2A agents and MCP servers are discoverable through AGNTCY directories — it's a layer beneath them, not a competitor. But we found no 2026 milestone announcements, version releases, or named production deployments. Technically alive, publicly quiet.

What we'd actually do about this

If you sell products online: UCP is the priority. A /.well-known/ucp manifest and clean structured product data is the highest-leverage work available right now. ACP for discovery, separately and second. Our agentic commerce practice exists for exactly this.

If you're building agent-facing infrastructure: MCP, and audit which spec revision you're on. The 2026-07-28 release deprecates enough that "we shipped MCP servers" doesn't tell you whether they'll work in a year.

If you're evaluating agent-to-agent workflows: A2A cleared the stability bar in March. The reason to wait is gone.

If you're planning agentic media: Don't pick yet. AdCP and AAMP are genuinely unresolved, and picking early here has real switching costs.

If someone is selling you a full-stack agentic solution: ask which of these they've implemented, which spec version, and when they last checked. The honest answer involves dates.

We re-verify this page quarterly against primary sources. If something here has gone stale, tell us — we'd rather fix it than defend it.