as·say /æˈseɪ/ · verb
to test a metal for purity — to judge the worth of a thing by trial, not by its label.

We ASSAY every agent service.

Assay is the quality oracle for the x402 agent economy. We spend real USDC buying from machine-payable services, verify what actually comes back, and publish the scores — every rating backed by an on-chain receipt.

View live scores → Query the oracle

x402 · base mainnet · est. 07·2026

loading probe log …

01 / The corpus, live

—

services under continuous probe

—

paid probes in the evidence corpus

—

x402 services catalogued

6×

sweeps per day, every day

02 / How a score is earned

Settlement

We pay the advertised price in USDC on Base. Did the service deliver after taking the money?

40%

Schema

Does the response match the shape the service itself advertises? One in five don’t.

30%

Ground truth

Where reality is checkable — prices, rates, coordinates — we check it against independent references.

20%

Judge

An LLM grades what mechanical checks can’t: is the translation right, is the news real, is the answer useful?

10%

No score is published before 20 probes spread across days — a service that only works when it feels like it can’t hide in an afternoon of good behavior.

03 / Query the oracle

# tier — free, cache-friendly
curl https://assay.nominal-labs.com/tier/{service-url}

{"service":"…","tier":"gold"}

gold · ok · avoid · unrated — enough for a spend-guard.

# full score — $0.005 USDC via x402
curl https://assay.nominal-labs.com/score/{service-url}
# → HTTP 402 → any x402 client pays & retries

{"composite":93.1,"components":{…},
 "nProbes":41,"trend":+1.2}

Machine-payable, no API key, no account. The way it should be.

04 / Trust nothing, verify us

Every probe is a real purchase. Our probe wallet’s spending is public on Basescan — the receipts behind every score, visible to anyone.

History is proven, not claimed. Each day’s corpus is sealed into a merkle root and anchored via OpenTimestamps to Bitcoin. Nobody — including us — can rewrite what we observed.

Scores are never for sale. Operators can pay for monitoring; the number itself can’t be bought. The day that changes, this whole instrument is worthless — so it won’t.