Reachability · cache-validators
Crawlers revisit. With a validator they send one conditional request and receive an empty 304; without one they download the whole page every time, which is the traffic sites then complain about.
| Check id | cache-validators |
|---|---|
| Pillar | Reachability — Can an agent fetch your content at all, without a browser and without being blocked? |
| Weight within the pillar | 4 points |
| Share of the overall score | about 0.8 of 100 |
| Kind of change | Configuration or content — no engineering needed |
Two numbers rather than one, because a check's weight is inside its pillar and the pillar is a share of the whole. The largest check in the smallest pillar moves your score less than a middling one in the largest, and knowing which you are looking at is the difference between fixing the right thing and fixing the loudest thing.
Crawlers revisit. With a validator they send one conditional request and receive an empty 304; without one they download the whole page every time, which is the traffic sites then complain about.
Worth saying plainly: this is not a search-engine ranking factor and passing it will not move you up a results page. It measures something else — whether software with no browser, no JavaScript and a few hundred tokens of budget can tell what your page is and do something with it. Those are the conditions an AI assistant reads you under, and they are much harsher than a browser's.
Send an ETag or a Last-Modified header on HTML responses and answer If-None-Match with a 304.
Most static hosts and CDNs do this already; it is usually an origin that generates HTML per request that does not.
ETag: "a1b2c3d4"
Last-Modified: Wed, 03 Sep 2026 09:12:00 GMT
Cache-Control: public, max-age=300, stale-while-revalidate=86400That remediation is the one the scanner itself offers when this check fails, read from the same code that does the scoring rather than written alongside it. If it were typed out separately it could drift from the check that judges it, which is the failure that makes published advice worthless.
Measured on 2026-09-06 against AX specification v1.5.1, across a sample of 292 public websites.
| Result | Sites | Share of those assessed |
|---|---|---|
| Failed | 150 | 51% |
| Warned | 12 | 4% |
| Passed | 130 | 45% |
| Did not apply | 0 | excluded from the shares |
The last row is kept out of the percentages deliberately. A check that did not apply to 0 of 292 sites is not a check most of the web passes, and folding those in is the commonest way this sort of table is used to say something untrue.
At 51% the web is genuinely split on this one, so it is neither table stakes nor a differentiator on its own.
npx axray-cli your-site.com
All 70 checks against one URL, this one among them, with what was found rather than only whether it
passed. Add --min 70 in a pipeline and the command exits non-zero below that score, so a
change that breaks what agents can read fails the build instead of shipping.
Crawlers revisit. With a validator they send one conditional request and receive an empty 304; without one they download the whole page every time, which is the traffic sites then complain about. It sits in the Reachability pillar of the Agent Experience rubric and is worth 4 points within that pillar, which works out at about 0.8 points of the overall score out of 100.
Send an ETag or a Last-Modified header on HTML responses and answer If-None-Match with a 304. Most static hosts and CDNs do this already; it is usually an origin that generates HTML per request that does not. It is a configuration or content change rather than an engineering one, so it can usually ship the same day.
No. Of 292 public sites where this check applied, 150 failed it — 51%. The measurement was taken on 2026-09-06 against AX specification v1.5.1, and no site is named.
Run npx axray-cli your-site.com from a terminal. It runs all 70 checks against one URL and prints this one among them, with what it found rather than only whether it passed. It is free, needs no account and installs nothing.
Can an agent fetch your content at all, without a browser and without being blocked?
See how your own page does on this check and the other 69, with the fixes ordered by how many points each one recovers. One scan, no account.