Did My Agent Lie? The Quick Receipt Check
Last updated: 2026-10-09
Plain answers about using Zambo, keeping your work, and checking receipts. A receipt shows what Zambo recorded for one call. It does not prove the answer is right.
Your agent says the task is done. Here is how to check instead of arguing with the transcript. The method: each executed tool call through Zambo returns a verifiable receipt. A planned or preview result is not an execution-success receipt. No receipt, no proof. Three checks settle it.
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Check 1: Ask for the receipt ID
"Done" is not an artifact. Ask the agent for the receipt ID of the call. If it cannot produce one, the work is unverified.
Check 2: Open the receipt and compare the hash
For developers
Open the receipt at its public page. Compare the result summary and the result hash against what the agent claimed. The sha256 hash means any alteration after the fact breaks the match.
Check 3: Check the timestamp
The receipt carries a timestamp. If it is from before you asked, or from a different session, the agent is citing old or borrowed work.
Make every future call checkable
Route tool calls through the Zambo connection Zambo link with a stable session id, as in the install guide. Then checks 1 through 3 apply to each executed call that returns a receipt.
Try it now (paste and run)
For developers
SESSION_ID="recipe-lie-check-$(date -u +%Y%m%dT%H%M%SZ)-$$"; curl -fsS --max-time 45 -w '\nHTTP %{http_code}\n' https://zambo.dev/mcp -H 'Content-Type: application/json' -H 'Accept: application/json, text/event-stream' --data-raw "{\"jsonrpc\":\"2.0\",\"id\":\"recipe-check\",\"method\":\"tools/call\",\"params\":{\"name\":\"zambo_universal\",\"arguments\":{\"need\":\"Find the current ETH/USD price from a read-only source and return the source.\",\"_session_id\":\"$SESSION_ID\"}}}"For developers
Open the returned receipt id at https://zambo.dev/run/<receipt-id> and confirm its result hash matches the tool output.
Frequently asked questions
What if my agent used a different tool?
Then there is no Zambo receipt for that call. The check covers calls that went through the receipting Zambo link. That is the point.
Can a receipt be faked?
The receipt is minted by the server at execution time with a hash of the actual arguments and result. Altering it breaks the hash.
Does this cost anything?
No. 20 calls per tool per day are free with no account.
Where do I verify?
For developers
At https://zambo.dev/verify or at any https://zambo.dev/run/ receipt page, using the receipt id.
Try Zambo
For developers
Run your first verified call at https://zambo.dev/install/ and check any receipt at https://zambo.dev/verify.