Last updated: August 21, 2026
You opened PageSpeed Insights to check a slow page and noticed a new category: Agentic Browsing.
Some checks passed. One says Not applicable. Others mention llms.txt and WebMCP.
Should you worry?
No. Agentic Browsing measures whether an AI agent can understand and use your page. It is not a Google ranking factor, and a failed check is not an SEO penalty.
Here’s what the checks mean and which ones deserve your attention.
What Is Agentic Browsing?
Agentic Browsing is an experimental Lighthouse category in PageSpeed Insights and Chrome DevTools.
Traditional Lighthouse checks ask:
Is this page usable for people?
Agentic Browsing asks:
Can software understand this page and complete a task without guessing?
That means identifying buttons, understanding form fields, reading page structure, and interacting with stable content.
The category currently focuses on:
- Accessibility and semantic structure
- Cumulative Layout Shift (CLS)
llms.txt- WebMCP
The score is based on applicable checks. A result marked Not applicable is not a failure.
Important: Agentic Browsing is a readiness signal, not a ranking system.
1. Accessibility: Give Every Element a Clear Meaning
Agents, screen readers, and other automated tools rely on semantic HTML and accessible names.
Avoid clickable <div> elements and unlabeled inputs:
<div class="btn" onclick="submitForm()">
<svg><use href="#icon-send"/></svg>
</div>
<input type="text" placeholder="you@company.com">
Use real controls and labels instead:
<button type="submit">
<svg aria-hidden="true"><use href="#icon-send"/></svg>
Send reset link
</button>
<label for="email">Email address</label>
<input
id="email"
name="email"
type="email"
required
autocomplete="email"
>
The key improvements are:
- Use
<button>for buttons - Use
<label>for form fields - Use meaningful input types
- Hide decorative icons from assistive technology
You can quickly find unlabeled controls in DevTools:
[...document.querySelectorAll('button, a, input, select, textarea')]
.filter(el => {
const name =
el.getAttribute('aria-label') ||
el.labels?.[0]?.textContent ||
el.textContent?.trim() ||
el.getAttribute('title');
return !name;
})
.forEach(el => console.warn('No accessible name:', el));
Priority: high. This improves accessibility, usability, and machine readability.
2. CLS: Keep the Page Stable
Agentic Browsing also checks Cumulative Layout Shift, a Core Web Vital.
If content moves after loading, an agent—or a human—may click the wrong element.
The standard thresholds are:
| CLS | Verdict |
|---|---|
| 0.00 to 0.10 | Good |
| 0.10 to 0.25 | Needs improvement |
| Above 0.25 | Poor |
Common fixes include:
Add image dimensions
<img
src="hero.webp"
width="1200"
height="630"
alt="Acme dashboard overview"
>
Reserve space for embeds
<div style="aspect-ratio: 16 / 9; width: 100%;">
<iframe
src="..."
loading="lazy"
title="Product tour"
></iframe>
</div>
Avoid injecting banners into the page flow
.cookie-banner {
position: fixed;
inset-inline: 0;
bottom: 0;
}
Priority: high. CLS already affects mobile usability and Core Web Vitals.
3. llms.txt: Optional, Not an SEO Requirement
The llms.txt check looks for a file at:
https://yoursite.com/llms.txt
If the file is missing, Lighthouse may show Not applicable.
That does not mean your site is broken.
Google has stated that llms.txt is not required for Google Search and does not improve or reduce rankings.
A basic file might look like this:
# Acme Analytics
> Self-serve product analytics for small engineering teams.
## Docs
- [Quickstart](https://acme.dev/docs/quickstart.md)
- [REST API](https://acme.dev/docs/api.md)
- [Event schema](https://acme.dev/docs/events.md)
Consider creating one if you publish technical documentation or an API that AI tools may need to understand.
For a standard business website or blog, you can usually skip it.
Priority: low and situational.
4. WebMCP: Useful for Task-Based Websites
WebMCP lets a website expose structured actions to AI agents.
For example, instead of asking an agent to find a search box, type into it, and guess which button to click, you can expose a tool such as:
if ('modelContext' in document) {
const controller = new AbortController();
document.modelContext.registerTool({
name: 'searchProducts',
description: 'Search the product catalogue.',
inputSchema: {
type: 'object',
properties: {
query: {
type: 'string',
description: 'Search keyword or phrase'
}
},
required: ['query']
},
async execute({ query }) {
return await productStore.search(query);
},
signal: controller.signal
});
}
WebMCP is still experimental, so most websites do not need it yet.
It may be worth exploring if your site supports:
- Product searches
- Booking
- Quote generation
- Support tickets
- Account workflows
- Other task-based interactions
Priority: low for most sites.
How to Read the Report
A report might look like this:
Agentic Browsing 3/3 checks passed
Accessibility tree Passed
Cumulative Layout Shift 0.019 Passed
llms.txt Passed
WebMCP registered tools Not applicable
The important detail is that Not applicable is excluded from the score.
You can inspect the underlying Lighthouse report with:
npx lighthouse@latest https://example.com \
--only-categories=agentic-browsing
In the JSON output, notApplicable and informative do not mean failure.
Does Agentic Browsing Affect SEO?
No.
Agentic Browsing is a Lighthouse diagnostic category, not a Google ranking factor.
Your SEO priorities remain:
- Helpful content
- Crawlability and indexing
- Internal linking
- Mobile usability
- Structured data where appropriate
- Core Web Vitals
The good news is that several improvements overlap. Clear headings, semantic HTML, labeled forms, and stable layouts help users, search engines, assistive technology, and AI agents.
What Should You Do?
Use this priority order:
- Fix accessibility issues
- Improve CLS
-
Consider **
llms.txt**** if you publish technical documentation** - Explore WebMCP only if your site depends on completing tasks
Do not implement a technology simply because it appears in a new PageSpeed panel.
“Not applicable” is not a to-do item.
Agentic Browsing is still experimental, but its main lesson is practical: make your website clear, semantic, and stable.
That helps every kind of visitor—including people, search engines, assistive tools, and future AI agents.
Frequently Asked Questions
Is Agentic Browsing a Google ranking factor?
No. It is a Lighthouse category, not part of Google's ranking system.
Do I need llms.txt for SEO?
No. Google does not require it for Search rankings.
Why does my report say “Not applicable”?
It means Lighthouse found nothing to evaluate. This is common for WebMCP when no tools are registered.
Should I implement WebMCP?
Only if your website's main purpose involves completing actions such as searching, booking, purchasing, or submitting forms. WebMCP is still experimental.
Will these checks change?
Probably. Chrome describes Agentic Browsing and WebMCP as experimental and subject to change. Focus first on durable improvements such as accessibility and CLS.
Next Step
Not sure which Agentic Browsing checks your site needs?
Request a free technical SEO and Core Web Vitals audit
We'll review your key templates, separate meaningful issues from optional checks, and provide a prioritised action plan.
