What is the receipt test for AI agent vendors?

A five-step due diligence test: ask the vendor for a live run, demand a verifiable execution receipt for every tool call, recompute one cryptographic commitment yourself, ask how missing receipts would show up, and ask who minted the receipts. Vendors with real evidence chains pass in minutes; vendors with slides fail the first question.

Why is vendor due diligence different for AI agents?

The risk is operational, not just organizational. The agent acts, spends, reads, and writes on your behalf, so paperwork about policies cannot substitute for per-action proof. Due diligence has to verify what the system does, not what the vendor claims.

What should an AI agent contract require for auditability?

Verifiable execution receipts for every tool call touching your data, in an open format, retained for your audit window, delivered on demand. Naming AER-1, published as an IETF Internet-Draft, avoids vendor lock-in because anyone can verify the receipts with public conformance vectors.

What is a red flag in an AI agent vendor security review?

Receipts or logs written by the agent itself, evidence that requires the vendor's private console to check, and no answer for what a missing record looks like. Each one means the evidence is circular, gated, or silently deletable.

How do receipts help with AI agent cost honesty?

Per-call receipts tie every billed unit to a specific tool call with exact inputs and outputs. When the vendor's margin depends on unattributable spend, itemized verifiable receipts remove the hiding places.

AI Agent Vendor Due Diligence: The Receipt Test

The procurement problem

Every AI agent vendor promises accuracy, security, and auditability. The RFP responses all read the same. The demos all work. Then the contract is signed, the agent touches production data, and the first incident reveals the truth: the vendor's auditability was a dashboard, the security review was a questionnaire, and nobody can prove what the agent actually did.

Due diligence for agents cannot be paperwork alone, because the risk is operational. The agent will act, spend, read, and write on your behalf. The question is not whether the vendor has a policy. The question is whether the vendor can prove, per action, what its system did.

The receipt test, step by step

Ask for a live run. Have the vendor run their agent against a task you choose, in an environment you can observe.
Ask for the receipts. For every tool call in that run, ask for a verifiable execution receipt: tool, calling agent, timestamp, inputs, outputs, and a cryptographic commitment.
Recompute one commitment yourself. Take the canonical bytes from a receipt, hash them, and compare. You need no account and no vendor help.
Ask for a gap. Ask what happens if a receipt is deleted or a call is missing. The right answer involves sequence numbers and visible gaps; the wrong answer is a shrug.
Ask who minted it. If the agent wrote its own receipts, the evidence is circular. Receipts must be minted by the execution layer, outside the agent's reach.

A vendor that passes does it in minutes. A vendor that fails will explain why the test is unfair, which is itself the answer.

What the test reveals

Real evidence chains vs marketing. Passing vendors have per-call receipts wired into their runtime. Failing vendors have a logging roadmap.
Tamper posture. Receipts the agent cannot rewrite mean the vendor designed for adversarial review. Self-written logs mean they designed for demos.
Incident readiness. A vendor that can hand you receipts today can hand you evidence after an incident. One that cannot, cannot.
Cost honesty. Per-call receipts make per-call billing auditable, which is where vendor margin games hide.

Put it in the contract

The test is also a contract clause. Require verifiable execution receipts for every tool call touching your data, in an open format, retained for your audit window, delivered on demand. AER-1, published as the IETF Internet-Draft draft-zambo-aer1, is the open format to name: no vendor lock-in, public conformance vectors, anyone can verify.

The evidence standard to cite

Name AER-1 receipts in your vendor requirements: minted by the execution layer, SHA-256 commitment per call, independently verifiable. Read the format guide.

Run the test yourself first

Before you ask a vendor for a receipt, hold one yourself. The live demo mints a real AER-1 receipt for a real tool call, free, no signup. Recompute the commitment. That is the bar you are about to set.

Mint a receipt and learn the test in one minute.