The 6 Agentic AI Protocols Every SEO Needs to Know
A user asks Gemini: “Find me a task chair under $400 with lumbar support and free shipping. Order the best one.”
The AI doesn’t open a new tab. It doesn’t ask the user to click anything. Instead, it queries product databases, cross-references reviews, checks real-time inventory, compares shipping policies, and initiates a checkout — all without a human touching a single page.
These are all things the user would have done themselves, but now in a fraction of the time, with as much effort as it took to write the initial prompt.
Okay, we might not be quite at the stage where everyone is letting AI agents make all their purchases for them. But it’s no longer an unrealistic future.
What made that possible isn’t the AI models themselves. It’s the infrastructure we’re seeing become an increasingly important part of how modern websites are built. This infrastructure consists of a stack of protocols that tells AI agents how to find each retailer’s site, understand their catalog, verify their claims, and take action.
These protocols define how AI agents interact with your brand. And most SEOs have no idea they exist.
By the end of this article, you’ll understand what each protocol does, how they differ from one another, and why you need to pay attention to what’s going on underneath the hood of AI search if you want to stay visible going forward.
Why Protocols Matter for SEOs
Protocols determine whether an AI agent can interact with your brand programmatically, or whether it has to guess. Brands that can speak the agent’s language are more likely to not just be surfaced, but also recommended and, ultimately, interacted with to make purchases.
Think of how robots.txt and XML sitemaps became table stakes for search crawlers. Agentic protocols are shaping up to be that for AI agents.
Put simply: if you want agents to be able to take action on your site — whether that’s making a purchase, booking a table, or completing a form — you need to understand these protocols.
Note: We’re not suggesting that without these protocols AI agents and users will never access your site or buy from them. Agentic commerce is still pretty new, and even the protocols themselves are still evolving. But we believe that agents will increasingly act on behalf of users, and that the easier you make it for them to do that on your website, the better positioned you’ll be as agentic commerce becomes the norm.
The Protocol Stack: A Quick Map
These protocols aren’t competing standards fighting for dominance. They operate at different layers of the same stack, and most are designed to work together.
Here’s a quick breakdown of what these protocols do:
| Layer | What It Does | Key Protocols |
|---|---|---|
| Agent / Tool | Connects agents to external data, APIs, and tools | MCP |
| Agent / Agent | Lets agents hand off tasks to other agents | A2A |
| Agent / Website | Lets websites become directly queryable by agents | NLWeb, WebMCP |
| Agent / Commerce | Enables agents to discover products and complete purchases | ACP, UCP |
Note: As with everything AI, the agentic protocols we’ll give more details on below are constantly evolving. This means some platforms are yet to adopt some of the protocols, and the specifics of each protocol could also change over time.
MCP: Model Context Protocol
MCP is the universal connector between AI agents and external tools, data sources, and APIs.
How It Works
Before MCP, every AI tool needed a custom integration for every data source it wanted to access. If you wanted a chatbot to pull live pricing from your database and cross-reference it with your CMS, someone had to build a bespoke connection between those systems. Then rebuild it whenever either one changed.
MCP standardizes that connection. Think of it as USB-C for AI: one protocol that lets any agent plug into any tool, database, or website that supports it.
An agent using MCP can pull live pricing data, check inventory, read structured content from a site, or execute a workflow, all through the same interface.
The website or tool publishes an MCP server, and the agent connects to it. There’s much less need for custom integration work on either side.
Who’s Behind It
MCP was launched by Anthropic in November 2024. It has since been adopted by OpenAI, Google, and Microsoft. MCP is now governed by an open-source community under the Agentic AI Foundation (AAIF), a directed fund under the Linux Foundation.
As of early 2026, there are more than 10K MCP servers out there, making it the de facto standard for agent-to-tool connectivity.
What It Means for Your Brand
Structured data, clean APIs, and accessible HTML have always been good technical SEO. Now they’re also agent compatibility requirements. Brands with MCP-compatible data give agents something to work with. Brands without it force agents to scrape pages and infer meaning, which creates friction and can affect whether they recommend you.
A2A: Agent-to-Agent Protocol
A2A is the standard that lets AI agents from different vendors communicate, delegate tasks, and hand off work to one another.
How It Works
MCP lets an agent talk to tools. A2A lets agents talk to each other.
When a task is complex enough to need multiple specialist agents — like one for research, one for comparison, and one for completing a transaction — A2A is the protocol that coordinates them.
Each A2A-compliant agent publishes an “Agent Card” at a standardized URL (that looks like “/.well-known/agent-card.json”). This card advertises what the agent can do, what inputs it accepts, and how to authenticate with it. Other agents discover these cards and route tasks accordingly.
The result: agents from entirely different companies, built on different frameworks, running on different servers, can collaborate on a single user request. No custom-built connections required.
Who’s Behind It
Google launched A2A in April 2025 with 50+ technology partners, including Salesforce, PayPal, SAP, Workday, and ServiceNow. The Linux Foundation now maintains it under the Apache 2.0 license.
What It Means for Your Brand
As multi-agent workflows become more common, agents may evaluate your brand across multiple checkpoints before a human sees the result.
That chain might look something like this:
- A research agent surfaces your product from a broad category query
- An evaluation agent reads your reviews and checks the sentiment
- A pricing agent verifies your costs against third-party sources
- A trust agent cross-references your claims for consistency
A2A orchestrates that entire chain. If your data is inconsistent across sources, like if your pricing page says one thing and your G2 profile says another, the AI agent might filter your brand out as a contender. All before the user even sees you as an option.
NLWeb: Natural Language Web
NLWeb is Microsoft’s open protocol that turns any website into a natural language interface, queryable by both humans and AI agents.
How It Works
Right now, when an AI agent visits your website, it might have to make a lot of guesses. It scrapes your HTML, infers meaning from your content, and relies on your page being structured properly to be able to parse it effectively. There’s a lot of room for error.
Once a site implements NLWeb, any agent can send a natural language query to a standard “/ask” endpoint and receive a structured JSON response. Your site then answers the agent’s question directly, rather than the agent interpreting your HTML.
Every NLWeb instance is also an MCP server. A site implementing NLWeb automatically becomes discoverable within the broader MCP agent ecosystem without any additional configuration.
Who’s Behind It
NLWeb was created by R.V. Guha, the same person behind RSS, RDF, and Schema.org. (That’s no coincidence.) NLWeb deliberately builds on web standards that already exist, which means a lot of websites are close to NLWeb-ready right now.
Microsoft announced NLWeb at Build 2025 in May 2025. It’s open-source on GitHub. Early adopters include TripAdvisor, Shopify, Eventbrite, O’Reilly Media, and Hearst.
What It Means for Your Brand
For SEOs, NLWeb is a natural extension of work you may already be doing.
Schema markup, clean RSS feeds, and well-structured content are the foundation NLWeb builds on. Sites that have invested in structured data have a head start. Sites that haven’t are harder for agents to work with, but they can easily catch back up by implementing schema markup now.
Structured data already helps search engines, and it can make it easier for agents to understand and interact with your site too. That increases the value of technical SEO work you may have been putting off.
WebMCP
WebMCP is a proposed W3C standard that lets websites declare their capabilities directly to AI agents through the browser.
How It Works
NLWeb makes your content queryable. WebMCP goes one step further: it lets websites declare what actions they support. These actions could include “add to cart,” “book a demo,” “check availability,” and “start a trial.”
These capabilities are declared in a structured, machine-readable format. Instead of an agent scraping your UI and guessing how your checkout works, WebMCP gives it an explicit map, straight from the source (you).
Who’s Behind It
Google and Microsoft proposed WebMCP, and the W3C Community Group is currently incubating it. Chrome’s early preview shipped in February 2026, with broader browser support expected by mid-to-late 2026.
What It Means for Your Brand
WebMCP is the clearest preview of where agent-website interaction is heading.
Imagine you have two brands with similar products, similar pricing, and similar reviews. The one whose site declares clear, structured capabilities is easier for an agent to act on. The other requires guesswork.
Agents are likely to take the path of least friction, and WebMCP helps you reduce friction to a minimum.
ACP: Agentic Commerce Protocol
ACP is OpenAI and Stripe’s open standard for enabling AI agents to initiate purchases.
How It Works
ACP focuses specifically on the checkout moment. It creates a standardized way for an AI agent to complete a purchase on a merchant’s behalf, handling payment credentials, authorization, and security through the protocol itself.
Before ACP, an agent that wanted to complete a purchase had to navigate each merchant’s unique checkout flow. A different form, a different payment process, and a different confirmation step for every retailer. ACP standardizes this process.
Merchants integrate with ACP through their commerce platform, and once live, checkout becomes agent-executable. The user doesn’t have to do anything except approve.
ACP originally powered ChatGPT’s instant checkout functionality, but that has since been removed by OpenAI in favor of dedicated merchant apps. ACP may still power product discovery within ChatGPT, and may be used within these apps, but things are evolving fast.
Who’s Behind It
OpenAI and Stripe launched ACP in September 2025. It’s open-sourced under Apache 2.0, with platform support still expanding.
What It Means for Your Brand
If an agent has shortlisted your product and the user tells it to go ahead and pay, ACP is what allows the agent to complete the transaction. If your brand isn’t integrated with this workflow, you risk the AI agent getting stuck or being unable to complete that purchase.
The agent can recommend you, but it can’t buy from you. That gap will matter more as agentic commerce becomes the norm.
UCP: Universal Commerce Protocol
UCP is Google and Shopify’s open standard for the full agentic commerce journey, from product discovery through checkout and post-purchase.
How It Works
ACP focuses on the checkout moment, while UCP covers the entire shopping lifecycle.
An agent using UCP can discover a merchant’s capabilities, understand what products are available, check real-time inventory, initiate a checkout with the appropriate payment method, and manage post-purchase events like order tracking and returns. All through a single protocol.
UCP is built to work alongside MCP, A2A, and AP2 (Agent Payments Protocol), meaning it plugs into the broader agent infrastructure rather than replacing it.
Merchants publish a machine-readable capability profile. Agents then discover it, negotiate which capabilities both sides support, and proceed.
Who’s Behind It
Google and Shopify co-developed UCP, with Google CEO Sundar Pichai announcing it at NRF 2026. More than 20 launch partners signed on, including Target, Walmart, Wayfair, Etsy, Mastercard, Visa, and Stripe.
What It Means for Your Brand
When a user asks Google AI Mode to find and buy something, UCP determines whether your brand is in the conversation, and whether the agent can actually complete the transaction.
The machine-readability of your product data, the consistency of your pricing across sources, the clarity of your inventory signals: all of it feeds directly into whether an agent can successfully transact with you.
ACP vs. UCP: The Key Difference
ACP and UCP are often confused, and they do share some similarities, but here’s where they differ:
| ACP | UCP | |
|---|---|---|
| Built by | OpenAI + Stripe | Google + Shopify |
| Scope | Discovery and checkout layers | Full journey: discovery, checkout, and post-purchase |
| Powers | ChatGPT instant checkout and product discovery | Google AI Mode, Gemini |
| Architecture | Centralized merchant onboarding | Decentralized: merchants publish capabilities at /.well-known/ucp |
| Status (early 2026) | Live, wider rollout in progress | Live, wider rollout in progress |
ACP and UCP are complementary, not competing. A brand may eventually support both — one for ChatGPT’s ecosystem, one for Google’s.
For now, the practical question is: which platforms matter most to your customers, and where does your commerce infrastructure make integration easiest? Choose the protocol that aligns with your answer, or use both.
Example of Agentic Search Protocols in Action
These protocols don’t operate in isolation. Here’s what they might look like working together (note that this isn’t necessarily exactly what’s going on at each stage, and is just for illustrative purposes):
Scenario: A user asks Gemini: “Find me a comfortable task chair under $400 with lumbar support and free shipping. Order the best option.”
Step 1: MCP Activates
The agent uses MCP to connect to external tools: product databases, review platforms, retailer inventory feeds. It can query live data rather than relying on cached or trained knowledge.
Step 2: A2A Coordinates
The agent then coordinates with specialist agents published by brands and review platforms via A2A. One evaluates ergonomics reviews. One checks pricing consistency across sources. One verifies free shipping claims against each retailer’s actual policy page.
Step 3: NLWeb Answers Queries Directly
The agents query each retailer’s site. Brands with NLWeb implemented respond to the agent’s /ask query with structured data. This includes things like accurate inventory, real-time pricing, and product attributes. Brands without it force the agent to scrape and infer, slowing it down and potentially leading to them being skipped altogether.
Step 4: WebMCP Declares Available Actions
The “winning” retailer’s site has declared its checkout capabilities via WebMCP. The agent knows exactly what actions are available and how to initiate them without any guesswork.
Step 5: UCP Completes the Transaction
The purchase is executed via UCP, entirely within Google’s AI experience. The merchant’s backend communicates through the standardized API. The user gets an order confirmation, and they never visited a single product page.
Obviously this is the fully agentic scenario. In reality, not every purchase is going to be left entirely to an AI agent.
But even when a human wants to evaluate options before clicking buy, making it as easy as possible for the agent to make recommendations is still good practice. That’s why these protocols are worth paying attention to.
What SEOs Should Do Now
Understanding the protocol layer is step one. Here’s where to focus next:
1. Prioritize Machine-Readable Content Over Volume
Before adding more pages, make sure your existing pages can be parsed cleanly by an agent. That means:
- Having your pricing in plain text, not locked behind JavaScript drop-downs
- Using feature lists that don’t require interaction to reveal
- Including FAQ content that renders server-side
- Using schema markup on product and organization pages
An agent that can’t read your page can’t recommend or buy your products.
2. Audit Your Structured Data
NLWeb builds on Schema.org, RSS, and structured content that sites already publish. If you’ve invested in schema markup, you have a head start on NLWeb compatibility.
If you haven’t, this is now a double reason to prioritize it: it improves your search visibility and makes your site more easily queryable by agents.
3. Check Your Consistency Across Sources
Agents verify claims by cross-referencing your site, review platforms, and third-party content. If your pricing page says one thing and your Capterra profile says another, agents can flag the discrepancy and lose confidence in your brand, making the recommendation or purchase less likely.
Audit for cross-source consistency the same way you’d audit NAP consistency in local SEO. It’s the same underlying principle, just for a different kind of crawler.
4. Get on the ACP and UCP Waitlists Now
These protocols are in active rollout. Early adopters benefit from lower competition in agent-mediated commerce while the rest of the ecosystem catches up. Join Stripe’s waitlist for ACP access. And join Google’s UCP waitlist too.
For other protocols like MCP, talk to your dev team about making sure your site supports them.
5. Monitor Your AI Footprint as a Regular Practice
Search your brand in ChatGPT, Perplexity, and Google AI Mode. Are agents describing your product accurately? Is your pricing consistent with what they’re surfacing? Are competitors appearing where you aren’t?
This is the new version of checking your SERP presence, and it needs to become a recurring part of your workflow, not a one-time audit.
Understand how your brand is appearing in AI search right now with Semrush’s AI Visibility Toolkit. It shows you where you’re showing up, where you’re behind your rivals, and exactly what AI tools are saying about your brand.
What’s Next for Agentic Search Protocols?
The protocols we’ve discussed here are already live, but they’re still evolving.
WebMCP is still in early preview. ACP and UCP are mid-rollout. New protocols — for agent payments, agent identity, agent-to-user interaction — are still being drafted and debated.
But the SEOs that understand and implement these protocols correctly are the ones most likely to see success.
Find out where your brand stands right now with our free AI brand visibility checker.
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