# ToolVerificationHook

**Kind:** Type

**Source:** [`atloria-monorepo/libs/agent-core/src/runtime/types.ts`](https://github.com/sherkety/atloria/blob/main/atloria-monorepo/libs/agent-core/src/runtime/types.ts#L377)

Called after a tool executes. Can block the tool output from reaching the
model and inject corrective feedback instead.

Inspired by Claude Code's hooks system (exit code 2 = block + correct).

Return `null` to pass through normally.
Return a string to REPLACE the tool output with corrective feedback.

## Definition

```ts
(
  toolName: string,
  toolInput: string,
  toolOutput: string,
) => string | null | Promise<string | null>
```