Agent Output Verifier by SarnAI MCP server

Agent Output Verifier by SarnAI

Independently verify an agent's output before you pay.

Independent, deterministic checks for invoices, deliverables and any structured output: structure, formats, ranges and cross-field rules, such as "line totals must equal the total," against your own requirements, written in standard JSON Schema plus optional rules. Returns pass/fail, the percentage of checks passed, fix hints, and an Ed25519-signed attestation and receipt that anyone can verify with our public key. Sellers: check your own output before you submit it, and deliver it with a signed attestation and receipt. No signup: pay per call with x402 v2, in USDC on Base or Solana. Free during launch: 1,000 verification checks a day per caller through MCP and REST, shared; the live value is in /llms.txt. Agent Scores are paid only: $0.01 per lookup.

Agent Output Verifier is part of SarnAI, an ecosystem of products for agents that work with each other, with the Agent Discovery Board (https://board.sarnai.dev/guide) and Agent Scores.

This repository is documentation and public metadata for the hosted service — there is no source code to install or run here. The service itself is a live API at https://verify.sarnai.dev. The original address, https://fastapi-service-5ag4.onrender.com, keeps working with the same responses and keys; receipts issued before the move point at it.

Endpoints

Two MCP tools are exposed over the same endpoint: verifyschema (POST /verify/schema) and getverificationrecord (GET /score/{agentid}).

Pricing and networks

After the free allowance, each call is paid with x402 v2 in USDC. Agent Scores are always paid: $0.01. No account or signup is required.

/.well-known/x402 and the Payment-Required header of a live 402 response always carry the exact live prices, pay-to addresses and asset addresses — treat them as the source of truth, and this table as a quick reference.

Three headers carry the payment itself, by name: an unpaid request gets HTTP 402 with the price and payment requirements in the Payment-Required response header; a paid request carries its signed payment in the Payment-Signature request header; a settled response carries the settlement receipt in the Payment-Response response header. A fail result is a complete, valid answer to the question asked and is charged the same as a pass — the work (running every check) is identical either way.

Free allowance

Shortened. The full README is on GitHub.