Managed Agents web_fetch limited to URLs already seen in the session

In Claude Managed Agents, web_fetch now only fetches URLs that already appeared in the session, to reduce data exfiltration risk. Other URLs return a url_not_in_prior_context error.

Who is affected:

Claude Managed Agents that fetch URLs from system prompts, files or tool output.

What to do:

Send needed URLs in a user.message event.