Hooks can no longer call the Artifacts server or the cloud browser
An mcp_tool hook aimed at the Artifacts MCP server or the session's cloud browser is now refused, and permission hooks cannot approve cloud browser calls
You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
HooksArea: what it touches
ImprovementsKind: in v2.1.309,
ImprovementsSection of the release
Unclear It is not clear exactly which setups of the Artifacts server are covered by the refusal.
What
A hook is an action you set up to run automatically at certain points while Claude Code works. An mcp_tool hook calls a tool on an MCP server, which is an outside program that gives Claude Code extra tools. Claude Code already refused some of these hooks. It now also refuses an mcp_tool hook when it targets:
the Artifacts MCP server
the cloud browser in a cloud session, which is a web browser that runs in the cloud
The cloud browser rule only applies in sessions that have one. When it refuses a hook, Claude Code tells you to remove the hook or point it at another server.
A PermissionRequest hook runs when a tool call needs a permission decision. It now cannot approve a call to the cloud browser's tools or loosen the rules for them.
Why
A hook's tool call skips auto mode's safety check and your approval. Blocking it for these servers stops that shortcut. If you have hooks pointing at either one, they will stop working.
Read from
Names in the bundlemcp_tool
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 doubtIt is not clear exactly which setups of the Artifacts server are covered by the refusal.
Anthropic's release notes agreeFixed hooks that run in PowerShell not blocking when the hook's program exits with code 2, and on Windows PreToolUse and PermissionRequest…
