`canUseTool`

A Claude Code settings key, read out of the shipped bundle. No mined inventory carries it: everything below comes from what this site has written about it.

What it is

Background and forked agents now run your permission callback even when a hook says allow, and deny rules win.

Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.222.

Presence across releases

The miner has never read a build containing this name. It is here because a changelog entry of ours names it, which is evidence that it existed and not evidence of which releases carried it. The inventory starts at v2.1.138 and everything older than that was never mined.

Changelog entries naming it

v2.1.223permission_denied events fire even without a permission prompt
Headless and SDK runs now report permission denials even when no prompt was ever shown.

named in this entry
v2.1.222Forked and background agent queries require canUseTool by default
Background and forked agents now run your permission callback even when a hook says allow, and deny rules win.

named in this entry

Documentation pages

How the agent loop works mentions it Claude Code CLI
Intercept and control agent behavior with hooks mentions it Claude Code CLI
Configure permissions mentions it Claude Code CLI
Agent SDK reference - Python mentions it Claude Code CLI
Extend agents with skills mentions it Claude Code CLI
Subagents in the SDK mentions it Claude Code CLI
Agent SDK reference - TypeScript mentions it Claude Code CLI
Handle approvals and user input mentions it Claude Code CLI
Claude Code changelog mentions it Claude Code CLI
Environment variables mentions it Claude Code CLI
Hooks reference mentions it Claude Code CLI
Automate actions with hooks mentions it Claude Code CLI

A reference table page is one whose own table defines this name, and it is where the description above came from. A page that mentions it carries the name somewhere in its text and may say nothing about it at all. Every page carrying it.

Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the settings key does. All settings keys.