{"version":"2.1.323","anchor":"deferred-tool-calls-with-missing-required-arguments-fail-ear","canonical_anchor":"deferred-tool-calls-with-missing-required-arguments-fail-ear","heading":"Calls to not-yet-loaded tools with missing arguments are stopped early","tier":"notice","area":"Tool Search","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.323\/e\/deferred-tool-calls-with-missing-required-arguments-fail-ear","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.323","markdown":"### Calls to not-yet-loaded tools with missing arguments are stopped early\n\nA call to a deferred tool that leaves out required arguments is now stopped before it runs, and the model is told to call it again in full\n\n**What**\n\nSome tools are deferred: Claude Code lists them, but the model does not get their full description of required inputs until it looks them up. Claude Code now checks a call to such a tool for missing required arguments before it asks you for permission. If any are missing, the tool does not run. The model gets an `InputValidationError` with the text \"Missing required arguments\", telling it to call the tool again with all of them.\n\n**Why**\n\nIt saves a wasted step when the model calls a tool whose details it never loaded, and you are not asked to approve a call that would fail anyway.\n\n- Area: Tool Search\n- Tier: You'll notice\n- Useful: 1\/5\n- Signal: 1\/5\n- Scope: individual\n- Heads-up: no"}