{"version":"2.1.321","anchor":"posttooluse-hooks-cannot-rewrite-some-tool-outputs-user-see","canonical_anchor":"posttooluse-hooks-cannot-rewrite-some-tool-outputs-user-see","heading":"PostToolUse hooks are blocked from rewriting more tool results, with a visible notice","tier":"notice","area":"Hooks","scope":"individual","heads_up":true,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.321\/e\/posttooluse-hooks-cannot-rewrite-some-tool-outputs-user-see","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.321","markdown":"### PostToolUse hooks are blocked from rewriting more tool results, with a visible notice\n\nPostToolUse hooks can no longer change certain results, such as answers to Claude's questions or plans, and you now see a message when one tries\n\n**Unclear.** Exactly which tools are covered, and which part depends on the remote switch, is not stated.\n\n**What**\n\nA 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.\n\nFor 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:\n\n- 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.\"\n\n- 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.\"\n\n- a Slack result, with similar wording\n\nPart of this wider protection depends on a remote switch and a check for sessions run without an interactive terminal.\n\n**Why**\n\nIf 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.\n\n- Area: Hooks\n- Names: `PostToolUse`\n- Tier: You'll notice\n- Useful: 2\/5\n- Signal: 2\/5\n- Scope: individual\n- Heads-up: yes"}