How to Score 3/3 on PageSpeed's Agentic Browsing Check (llms.txt, Accessibility Tree, CLS)

A perfect 3/3 on PageSpeed's Agentic Browsing check comes down to three fixable things: a valid llms.txt file, a clean accessibility tree, and a stable layout. Here's exactly how to get each one green.

Google's new Agentic Browsing category in PageSpeed Insights grades your site on a pass/fail ratio. Most sites land at 2/3. The good news: the gap between where you are and a clean 3/3 is small, concrete, and entirely within your control. Let's close it, one check at a time.

Check 1 — Ship a valid llms.txt (the #1 reason sites score 2/3)

The single most common reason a site scores 2/3 instead of 3/3 is a missing llms.txt file. It's a plain-text file that lives at your domain root — https://yourdomain.com/llms.txt — and gives AI systems a clean map of your site.

A valid file needs a top-level H1 heading, a short description, and links to your key pages. Here's a minimal, passing example:

# Your Business Name

> One sentence describing what you do and who you serve.

A short paragraph of context an AI system can use to summarize you
accurately. State what is authoritative (your pricing and product
pages) so agents don't invent details.

## Services
- [Services](https://yourdomain.com/services): what you offer
- [Pricing](https://yourdomain.com/pricing): source of truth for prices

## Resources
- [Blog](https://yourdomain.com/blog): guides and articles
- [Contact](https://yourdomain.com/contact): get in touch

Common failures the check flags: a missing H1, a file that's too short, or one with no links. Fix those and this check turns green. (Note: llms.txt is still an emerging convention — but the PageSpeed check rewards having a valid one now.)

Check 2 — Clean up your accessibility tree

AI agents don't "see" your page the way you do — they read the accessibility tree, the structured representation browsers expose to assistive tech. If a control isn't named there, the agent doesn't know what it does. The three highest-impact fixes:

• Name every interactive element. Icon-only buttons need an accessible label. A magnifying-glass button should announce itself as "Search," not as an empty control.
• Label every form field. Every input needs an associated <label> (or aria-label). Placeholder text is not a label.
• Give images meaningful alt text. Decorative images get empty alt; content images describe what they show.

<!-- Invisible to an agent -->
<button><svg>...</svg></button>

<!-- Usable by an agent -->
<button aria-label="Add to cart"><svg aria-hidden="true">...</svg></button>

If your PageSpeed Accessibility score is already 90+, this check is usually close to passing already — the same fixes serve both.

Check 3 — Lock down layout stability (CLS)

Agents that screenshot your page to reason about it get confused when the layout jumps around as it loads. That instability is measured as Cumulative Layout Shift (CLS). Aim for 0.1 or lower. The usual culprits and fixes:

• Images without dimensions. Always set width and height (or a CSS aspect-ratio) so the browser reserves space before the image loads.
• Late-loading web fonts that reflow text. Use font-display: optional or preload your primary font.
• Injected banners and ads that push content down. Reserve their space with a fixed-height container.

Verify your 3/3

After each fix, re-run your URL. You can use Google's free tool directly, or our free Agent-Readiness Check, which reads the same Lighthouse signals and shows them in plain English. Work top-down: llms.txt first (biggest, easiest win), then the accessibility tree, then CLS.

Don't want to DIY?

If you'd rather not hand-edit HTML and hunt down layout shifts, our Agent-Readiness Audit does the whole thing for you: a full-site diagnosis across every template, a competitor benchmark, a ready-to-ship llms.txt, and a prioritized fix plan — with the fee credited toward implementation if you want us to do the work. Either way, 3/3 is very achievable, and being early is an advantage.