Most answer engine optimization checklists open with the same line: let the AI crawlers in. The crawlers they list are often the wrong ones.
Some popular checklists name GPTBot and Google-Extended as the access step and leave OAI-SearchBot out. OpenAI describes GPTBot as a training crawler. Google says Google-Extended does not affect inclusion in Google Search.
Each major engine publishes a page that says which crawler does what. This checklist starts from those pages, then sorts the rest of the usual AEO advice by whether any engine actually asks for it.
Key takeaways
- OpenAI, Anthropic, and Perplexity each run a separate crawler for search answers. In OpenAI's crawler documentation, OAI-SearchBot decides whether a site can appear in ChatGPT search answers, and GPTBot collects content for training.
- OpenAI states that "each setting is independent of the others." A site can refuse training and still appear in ChatGPT search. A site that blocks OAI-SearchBot drops out of those answers, even with GPTBot allowed.
- Google's crawler documentation says Google-Extended "does not impact a site's inclusion in Google Search," where AI Overviews and AI Mode find their links. It does govern grounding in the Gemini app.
- Google's page on AI features states that no AI text files, new machine-readable files, or special schema are needed. None of the four vendors' crawler pages says its crawlers read llms.txt.
What does AEO optimization cover?
AEO optimization is the work of making a site easy for answer engines to reach, read, and cite. It overlaps with generative engine optimization, and the AEO and GEO guide covers how the two terms relate. Of its three parts, access, content, and measurement, only access has rules the engines publish.
Which crawler decides whether a site appears in AI answers?
Each vendor runs up to three kinds of crawler. One builds the index used for answers, one collects training data, and one fetches a page when a user asks. Each is set separately in robots.txt.
| Engine | Decides inclusion in answers | Collects training data | Fetches on a user's request |
|---|---|---|---|
| ChatGPT (OpenAI) | OAI-SearchBot | GPTBot | ChatGPT-User |
| Claude (Anthropic) | Claude-SearchBot | ClaudeBot | Claude-User |
| Perplexity (Perplexity) | PerplexityBot | None listed; PerplexityBot "is not used to crawl content for AI foundation models" | Perplexity-User |
| Google AI Overviews and AI Mode (Google) | Googlebot (the page must be indexed in Search) | Google-Extended (Gemini models) | Not covered here |
OpenAI is the most explicit. Its page says sites opted out of OAI-SearchBot "will not be shown in ChatGPT search answers." Blocking GPTBot only signals that content "should not be used in training." ChatGPT-User "is not used to determine whether content may appear in Search."
Anthropic's page says disabling Claude-SearchBot "may reduce your site's visibility and accuracy in user search results." These pages say what each crawler is for, not how much allowing it raises citations. Microsoft Copilot is left out of this table because its documentation was not part of this review.
Does blocking AI training remove a site from AI answers?
Not on these vendors' own descriptions. The search crawler and the training crawler are separate switches. Training access and answer access are two decisions.
For legal and brand teams, that means a site can block GPTBot, ClaudeBot, and Google-Extended for data reasons. With the search crawlers still allowed, it keeps its route into ChatGPT search, Claude search, Perplexity, and Google AI Overviews. The reverse mistake is costlier: a site that blocks OAI-SearchBot is kept out of ChatGPT search answers, even with GPTBot allowed.
Google-Extended is the one partial exception: Google says it also governs grounding in Gemini Apps, meaning content supplied to the model at the moment a user asks. Blocking it can therefore affect answers in the Gemini app. Google Search and its AI features stay governed by Googlebot.
What do the engines say is not needed?
Google's AI features page is direct: "You don't need to create new machine readable files, AI text files, or markup to appear in these features. There's also no special schema.org structured data that you need to add." The guide to ranking in AI Overviews covers what Google does treat as a requirement.
llms.txt is a proposed convention, not a documented input. None of the OpenAI, Anthropic, Perplexity, or Google crawler pages says its crawlers read it. Publishing one costs little, but it does not belong on a checklist as a lever.
FAQ markup gets the same treatment. Valid structured data still supports the Search features it was built for, as long as it matches the visible text. Adding it only to win AI citations rests on a promise no engine has made.
What belongs on an AEO optimization checklist?
Each item below pairs the work with how to confirm it was done.
| Item | Source of the rule | How to check it |
|---|---|---|
| Search crawlers allowed: OAI-SearchBot, Claude-SearchBot, PerplexityBot, Googlebot | Each vendor's crawler page | robots.txt, plus server logs showing those crawler names arriving |
| Training crawlers decided on separately: GPTBot, ClaudeBot, Google-Extended | Each vendor's crawler page | A written decision, so a later block does not touch search access by accident |
| Pages indexed and allowed to show a snippet in Google Search | Google's AI features page | Search Console indexing report |
| Firewall and bot-protection rules let the crawlers' published network addresses through | OpenAI and Perplexity both publish address lists | Log entries showing the crawlers reaching the site |
| Content written to answer the question in the first lines of each section | Observed practice, not an engine rule | Editorial review |
| Original data and credible third-party coverage | Observed practice, not an engine rule | Editorial review |
The first four rows are pass or fail. The last two are reasonable investments with no promised return, and the guide to content AI engines cite covers them in depth.
How can a team tell whether a change worked?
Slowly, and on more than one run. AI answers change from day to day with nothing changed on the site. One check after a robots.txt fix or a rewrite cannot tell the effect apart from that movement.
The AEO tracking guide shows how much the numbers move on their own and how to read a report against that. Access fixes show up first in server logs, as the search crawlers start arriving, and only later in the answers.
Zumi, an AI Search Intelligence Platform, tracks how a brand appears in answers on each engine. A change in access or content can then be read against the brand's own baseline. Book a demo to see the reports on a brand's own questions.
Sources
- OpenAI, "Overview of OpenAI crawlers", checked 12 October 2026.
- Anthropic, "Does Anthropic crawl data from the web, and how can site owners block the crawler?", checked 12 October 2026.
- Perplexity, "Perplexity crawlers", checked 12 October 2026.
- Google Search Central, "Google's common crawlers", checked 12 October 2026.
- Google Search Central, "AI features and your website", last updated December 2025.