Type●Since v1.4

WhenPredicate

Predicate controlling whether a given tool call triggers an interrupt.

Receives a ToolCallRequest and returns true to interrupt or false to auto-approve the tool call.

The request is constructed with tool set to undefined and runtime set to the node-level Runtime, so it reflects the batch (afterModel) context rather than a per-call tool execution.

WhenPredicate: z.infer<typeof WhenFunctionSchema>

Example

import { type WhenPredicate } from "langchain";

// Only interrupt delete_file calls targeting /etc
const when: WhenPredicate = (request) =>
  String(request.toolCall.args.path ?? "").startsWith("/etc");

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WhenPredicate

Example

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WhenPredicate

Example