The Agentic Browsing category evaluates how well your site is constructed for machine interaction through a set of deterministic audits.
How the category is scored
Unlike other Lighthouse categories, the Agentic Browsing category does not have a weighted average score from 0 to 100. Because the standards for the agentic web are still emerging, the current focus is to gather data and provide actionable signals rather than a definitive ranking.
Instead of a score, the report displays:
- A fractional score: A ratio showing how many agentic readiness checks your site passes.
- Pass or Fail status: Specific audits may emit errors or warnings if technical requirements (like WebMCP schema validity) are not met.
- Informational counts: The category header may include a pass ratio to help you observe overall progress at a glance.
Why results fluctuate
While the audits are deterministic, your results may fluctuate due to changes in how your site registers its tools or responds to agentic requests. Common causes include:
- Dynamic tool registration: If your site registers WebMCP tools using JavaScript (Imperative API), the timing of these registrations can affect whether they are captured during the Lighthouse snapshot.
- Variability in A11y tree construction: Significant changes to DOM size or complexity can impact the structure of the accessibility tree, which is a core metric for agentic navigation.
- Cumulative Layout Shift (CLS): Layout shifts caused by ads, images without dimensions, or injected content can move elements between the time an agent identifies them and the time it attempts an interaction.
How audits are determined
Lighthouse uses a set of deterministic signals to evaluate your page. This ensures that the audits are reproducible and suitable for integration into CI/CD pipelines.
WebMCP Integration
Lighthouse calls the Chrome DevTools Protocol (CDP) WebMCP domain to monitor
tool registration events. It verifies both declarative tools (defined in HTML)
and imperative tools (defined in JS).
Agent-Centric Accessibility
Agents rely on the accessibility tree as their primary data model. Lighthouse filters a specific subset of accessibility audits that are critical for machine interaction, such as:
- Names and labels: Ensuring every interactive element has a programmatic name.
- Tree integrity: Verifying that roles and parent-child relationships are valid.
- Visibility: Confirming that content is not hidden from the accessibility tree while being interactive.
Stability and Discoverability
- Cumulative Layout Shift (CLS): Measures visual stability, which is critical for agents relying on element positioning.
- llms.txt: Checks for the presence of a machine-readable summary at the domain root.
What can developers do to improve?
To improve your site's agentic readiness:
- Adopt WebMCP: Use the WebMCP API to explicitly expose your site's logic and forms to AI agents.
- Ensure a sound a11y tree: Prioritize semantic HTML and proper ARIA labeling, as these are the "machine-eye view" of your page.
- Optimize for stability: Reduce layout shifts to ensure that agents can reliably interact with your UI without elements moving unexpectedly.
Feedback
If you encounter bugs or have suggestions for changes to the agentic browsing audit: