Question

An expense-reimbursement agent processes employee requests through a `process_reimbursement` tool. Company policy requires manager approval before funds are disbursed for reimbursements above $500. The agent handles hundreds of requests each day, and the threshold enforcement must be tamper-proof regardless of how the agent is prompted. Which design ensures that the $500 approval threshold cannot be bypassed?

Accepted Answer

A. The process_reimbursement tool accepts amount and details, and internally enforces the threshold: amounts <$500 are auto-disbursed and the tool returns a success confirmation; amounts >$500 cause the tool to create a pending approval request and return a status indicating manager review is pending.

Answer

The process_reimbursement tool accepts an approved_by_manager: boolean parameter. The system prompt instructs the agent to only set this to true after confirming that a manager has approved the request. A nightly audit script reviews all reimbursements where approved_by_manager was set to true.

Answer

Provide two tools: auto_reimburse (hard-coded limit of $500) and request_manager_approval. Include detailed system prompt instructions telling the agent to check the amount and call the appropriate tool. Add a PostToolUse hook that logs which tool was called for auditing.

Answer

Implement the threshold check in a PreToolUse hook that inspects the amount parameter before process_reimbursement executes. If the amount exceeds $500, the hook modifies the tool call to add a requires_approval: true flag, which the tool checks before disbursing.