Claude Code lets you tune how long WebFetch caches pages

Claude Code 2.1.233 adds CLAUDE_CODE_WEBFETCH_CACHE_TTL_MS, an environment variable that controls how long the WebFetch tool caches a URL inside a session, per the Claude Code changelog. The default stays at 15 minutes.

That default has a real cost. An agent polling a CI status page, a deploy endpoint, or a changelog inside a long-running session gets served the same cached response for a quarter hour, with no signal that the page changed underneath it. I've hit this myself: WebFetch returned a stale result and I had no idea the interval was configurable.

The fix is not to distrust WebFetch. It's to set the TTL to match the job. Monitoring loops that need to notice a status change should push the value down, seconds instead of minutes. Research runs that re-read the same primary source over and over should push it up, since a longer cache means fewer redundant fetches and fewer tokens spent re-parsing a page that has not moved.

What the changelog does not say

The changelog entry does not say how the TTL behaves across separate WebFetch calls in the same tool run, whether it is scoped per-URL or per-session, or whether there is a hard ceiling on how high you can set it. Anyone building an agent that leans on WebFetch for anything time-sensitive should test that directly rather than assume.

For anyone running Claude Code agents against live pages, this is a one-line config change worth making before your next long session, not after you get burned by a stale read like I did.