MarginGuard answers with evidence: one paid call returns a deterministic verdict grounded in half a million real market prices — with the unit economics, the confidence tier, and a receipt hash your agent can hold you to.
| product | arroz 1kg · PHL |
| evidence tier | T1_OFFICIAL_SURVEY |
| confidence | 0.80 |
| market median | 62.29 PHP · 15 obs |
| breakeven / floor | 35.56 / 45.71 |
| receipt | 661f36f49cdbaa51a10980ba119b93be… |
Every call resolves to exactly one action through a deterministic policy ladder — same inputs, same verdict, same hash, every time.
Available as REST and as MCP endpoints — point any agent at the server and it can discover, pay, and call on its own.
| tool | price / call | what you get |
|---|---|---|
| check_margin | $0.05 | Full decision packet: verdict, confidence, evidence tier, unit economics, market stats, flags, reasoning, receipt hash. |
| get_price_floor | $0.02 | Breakeven price and minimum viable sale price for your cost and fee structure at a target margin. |
| contribute_price | free | Add a real observed price to the community pool; pools with 3+ independent contributors can ground decisions. |
| coverage | free | Honest per-source data coverage — including where we have nothing. |
| health | free | Liveness and data freshness. |
No API keys, no subscriptions, no invoices. Your agent pays per answer over the x402 protocol, settled in USDT on X Layer.
POST /v1/check_margin — the server replies
402 with a signed price offer in the
PAYMENT-REQUIRED header.
The agent's wallet signs the offer (EIP-3009) and retries with
PAYMENT-SIGNATURE. Same proof + same request = charged once,
cached packet returned.
Verdict returns with a PAYMENT-RESPONSE header carrying the
on-chain settlement transaction. Money and answer move together.
The money path is pure decimal arithmetic — no floats, no LLM, no clock reads. Everything else follows from that.
Same inputs produce a byte-identical packet and an identical SHA-256 receipt. Reproducibility is the dispute defense.
Every number in the packet's reasoning must exist in the packet's data, or the packet is refused before it's served.
Freshness gates, a 3-observation grounding rule, and conflict caps —
and coverage reports zeros where the data has nothing.
WFP surveys via HDX, Open Prices (ODbL, attributed), marketplace aggregates, community contributions — every row carries provenance.