Index eligibility: definition and how it works

Index eligibility is the set of conditions a page must meet before a search engine or AI answer engine is allowed to show it. It is a gate, not a ranking.

The brief version: eligible means the engine may show you. Shown means it did. Google draws this line itself in its AI features documentation: "Indexing and serving isn't guaranteed."

Snippet eligibility is a narrower piece of the same idea. A page can be indexed but barred from showing a text excerpt. For Google's AI features, that excerpt permission is part of the requirement.

Google AI Overviews and AI Mode

Google states the rule in one sentence: "To be eligible to be shown as a supporting link in AI Overviews or AI Mode, a page must be indexed and eligible to be shown in Google Search with a snippet, fulfilling the Search technical requirements. There are no additional technical requirements."

In practice, a page fails that test when:

• robots.txt blocks Googlebot from crawling it
• a noindex directive keeps it out of the index
• nosnippet or max-snippet:0 removes its snippet permission
• the Search Console generative AI control is switched off for the property

That last control is opt-out. Inclusion is the default for all properties, and child properties inherit the parent's setting. As of October 2026 it is still rolling out to a subset of owners, so a property can be excluded without anyone noticing.

For finer control, data-nosnippet hides one section from display while the rest of the page stays eligible.

Other engines

Each engine sets its own gate. OpenAI says sites opted out of OAI-SearchBot "will not be shown in ChatGPT search answers." Its help centre adds a second condition: your host or CDN must allow traffic from OpenAI's published search bot IP addresses. Robots.txt alone is not enough if a firewall returns 403.

Eligibility is the one stage of AI visibility that you fully control. Whether a model retrieves your page for a given question, and whether it cites you, sits with the engine.

Otterly's published 2,000 AI blogs experiment shows the gate working. Google deindexed both test sites, and Google's AI surfaces almost never cited them afterward. Bing kept them indexed, and Microsoft Copilot, which grounds on Bing, kept citing them. An engine cannot cite what its index no longer holds.

The next move is a per-engine check:

1. Confirm the page is indexed in Google Search Console and Bing Webmaster Tools separately.
2. Scan templates for stray noindex and snippet directives. The accidental noindex audit walks through it.
3. Check that robots.txt and your CDN both let each search crawler in.

If all three pass and you still never appear, the cause is selection, not eligibility. Why indexed pages miss AI Overviews covers that case.

• "Eligible means I'll be cited." No. Eligibility only removes a block. Google says serving isn't guaranteed.
• "I need to opt in to AI Overviews." No. Inclusion is the default. The Search Console control is an opt-out. See whether you need to opt in.
• "Schema or an llms.txt file makes a page eligible." Google says there are no additional requirements and no special optimizations needed for AI Overviews or AI Mode. Structured data is not required for generative AI search.
• "noindex and nosnippet do the same thing." They do not. One removes the page from the index, the other removes the excerpt. The noindex vs nosnippet comparison sets out the difference.
• "Eligible in Google means eligible everywhere." Each engine runs its own crawler, index and access rules.

• max-snippet: caps snippet length; a value of 0 removes snippet eligibility.
• data-nosnippet: hides a section from snippets and AI summaries without removing the page from the index.
• Crawler access: whether a bot may fetch the page at all, set by robots.txt and your network edge.
• Retrieval: whether an engine pulls an eligible page into its context for a specific query.

For what happens after the gate, read your control and Google's in AI Overviews.

Can a page blocked by robots.txt still be eligible for AI Overviews? Generally no. Google's AI features require a page to be indexed and eligible for a snippet, and a robots.txt block on Googlebot stops Google crawling the content. There is no separate robots.txt token for AI Overviews or AI Mode. Googlebot rules are the control, so blocking Googlebot affects Search and its AI features together.

Does blocking GPTBot make me ineligible for ChatGPT search? No. OpenAI's crawler settings are independent. GPTBot governs training use only. OAI-SearchBot governs whether your site can appear in ChatGPT search answers. A site can block GPTBot and allow OAI-SearchBot. OpenAI also asks that your CDN or host allow traffic from its published search bot IP ranges.

How do I check whether my property opted out in Search Console? Open the property in Search Console and look for the generative AI inclusion control. As of October 2026, Google is still rolling it out to a subset of owners, so you may not see it. If you manage child properties, check the parent too, because children inherit the parent's setting by default. No outside crawler can see this setting.

Is snippet eligibility the same as having a featured snippet? No. Snippet eligibility means Google is allowed to show a text excerpt from your page. A featured snippet is a specific result format Google may or may not choose to show. You can be snippet eligible without ever earning a featured snippet. For AI Overviews, the eligibility is what matters.