You'll noticeTier: how much it should matter to you
1Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
PermissionsArea: what it touches
ImprovementsKind: in v2.1.284,
ImprovementsSection of the release
Unclear Exactly which bracketed addresses got past the check before is not settled.
What
In auto mode, the Bash tool can take an allowed_domains list for a single command, naming the hosts that command may reach over the network. Claude Code already rejected entries that write a loopback address (your own machine) or an IPv4 host in a disguised form, such as an IPv4-mapped or NAT64 IPv6 address. That check now also looks inside a leading pair of square brackets. Bracketed forms, including ones with a port number, can no longer get past it. The error still tells you to allow the plain dotted IPv4 address or the real host name instead.
Why
In auto mode Claude supplies the host list itself, so this closes a way around the sandbox's network check. The sandbox is the walled-off environment that commands run in.
Read from
Names in the bundleallowed_domains
Since it was published
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Added sinceA small documentation edit on server-tools touched a line naming allowed_domains after this was published.[Claude Managed Agents](https://platform.claude.com/docs/en/managed-agents/overview) uses the same `allowed_domains` and `blocked_domains` fields on the `web_search` and `web_fetch` entries of the agent toolset. On Managed Agents, each lis…agents-and-tools/tool-use/server-toolssee the edit
Confirmed sinceAnthropic's documentation has since written up allowed_domains, on Agents.- `allowed_domains: optional array of string`api/beta/agentssee the edit
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtExactly which bracketed addresses got past the check before is not settled.
Anthropic's documentation agreesAnthropic's documentation has since written up allowed_domains, on Agents.
