Claude adds organization controls for web fetch
Anthropic’s October 20, 2026 release notes added organization controls for Claude web fetch. Administrators can disable fetching or configure an allowed or blocked domain list in the Console’s Capabilities page. Managed Agents also enforces organization restrictions alongside each agent’s tool settings.
The same entry distinguishes older web search changes. Managed Agents has followed the organization’s search switch since October 6 and its search domain restrictions since October 14. Those are separate from the October 20 fetch update.
The switch changes two error paths
The web fetch guide says disabling the capability makes a Messages API request containing the tool fail with HTTP 400 and invalid_request_error. In a Managed Agents session, a web_fetch call instead returns an error to the agent while the session continues.
That differs from an ordinary fetch tool failure inside an accepted Messages API request. Those responses carry HTTP 200 with an error in the body, which Claude receives before continuing. A successful HTTP status therefore does not establish that a page was fetched.
Redirects must pass the combined restrictions
The Managed Agents guide, marked beta, says a fetched URL must pass both the organization’s domain restrictions and the agent’s tool lists. Every redirect destination must pass too. A rejected fetch produces an error result, with is_error set to true and the code url_not_allowed.
Each agent tool entry accepts either allowed_domains or blocked_domains, never both. Lists contain 1 to 64 domains. Fetch entries require plain ASCII hostnames without paths. A domain includes its subdomains. Empty lists are rejected, while omitting the field or using null removes that entry’s own restriction.
In a cloud environment with limited networking, a session creation or update is rejected with HTTP 400 if an enabled web tool’s allowed domain is outside the environment’s permitted hosts. At runtime, an excluded fetch host instead produces an error result.
Cloud environments add another boundary
The environment guide explains that limited networking applies allowed_hosts to web search and fetch even though those tools run on Anthropic’s servers. Package manager and MCP allowances add no hosts for these tools. If the host list is empty, neither tool returns a page or search result.
A host allowed there also becomes reachable from the sandbox. Unrestricted networking and environments hosted by the customer do not impose this environment limit on the web tools. Their tool domain restrictions remain a separate control.
Domain selection leaves residual risk
Anthropic warns that web fetch can expose sensitive data when combined with untrusted input. Its URL checks limit fetching to addresses already present in permitted conversation sources, excluding URLs found only in Claude’s own output. The guide still identifies residual risk.
ByteForward reviewed the documentation without running API tests or changing an account’s controls.
Related coverage explains Claude Platform tracing for API requests and agents.
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