Unclear Whether the plugin system that runs this hook is switched on by default is not known.
Plugins can now take part in permission checks through a new tool.check hook. A plugin is an add-on that extends Claude Code. A hook is an event that a plugin can respond to. When Claude Code checks whether a tool may run, a plugin can now answer allow, deny or ask.
For built-in tools and some MCP tools, Claude Code limits what a plugin's answer can do. MCP tools are tools that come from outside services connected to Claude Code. For these tools Claude Code ignores:
- any allow answer from a plugin
- any plugin answer at all when Claude Code's own permission check has already denied the tool
When Claude Code ignores a plugin's answer, it records that it kept its own decision, and that plugins can only make that tool's permission stricter in this session.
Plugins now have a way to add extra caution to tool use, such as asking first or blocking a tool. They cannot use this hook to quietly grant a built-in tool more access than your own permission settings give it.
Whether the plugin system that runs this hook is switched on by default is not known.