Unclear Exactly which tools are covered, and which part depends on the remote switch, is not stated.
A hook is a script you configure to run at a set moment. A PostToolUse hook runs after Claude uses a tool, meaning one of the actions it can take, and it can try to replace what that tool returned.
For some tools, such attempts are now dropped and a message is shown to you. The protection used to cover only account memory servers, and it was silent apart from a log line. It now also covers other results, including:
- the answer to a question Claude asked you: "A hook tried to change the answer to Claude's question, which it may not do in this session. Claude read the answer unchanged."
- a plan: "A hook tried to change the plan, which it may not do in this session. Claude read the plan without the hook's change."
- a Slack result, with similar wording
Part of this wider protection depends on a remote switch and a check for sessions run without an interactive terminal.
If you write PostToolUse hooks, some of their changes will now be ignored. Claude reads the original result instead. The new message makes it clear when this has happened.
Exactly which tools are covered, and which part depends on the remote switch, is not stated.