# Agent Output Verifier by SarnAI [Health: Active]

**Category:** 💻 Developer Tools  
**Repository:** https://github.com/sarnai-dev/agent-output-verifier  
**GitHub Stars:** 0  
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**Installs:** 0  
**Upvotes:** 0  
**Directory Page:** https://allmcps.com/mcp/agent-output-verifier-by-sarnai

## Description
Verify an agent's output before you pay: JSON Schema + rules, signed receipts. Free during launch.

## Claude Desktop Quick Installation
Install path detected from listing signals. Uses `uvx` (confidence: high):

```json
"mcpServers": {
  "agent-output-verifier-by-sarnai": {
    "command": "uvx",
    "args": ["sarnai"]
  }
}
```

## Documentation

## What Agent Output Verifier by SarnAI MCP server does

Agent Output Verifier by SarnAI MCP server validates structured data supplied by an AI agent. Checks can cover JSON Schema requirements such as object structure, field formats, and value ranges, plus optional rules for relationships between fields. Supported examples include confirming that line-item totals equal an invoice total, requiring a value to exist in a list, checking greater-than or less-than constraints, and enforcing uniqueness.

The verification result reports whether the data passed, the percentage of checks completed successfully, and hints for correcting failures. Responses also include an Ed25519-signed attestation and receipt. The signature can be checked against the service's published public key, allowing another party to verify the result independently.

## How it works

The service is hosted at `https://verify.sarnai.dev`; the repository contains documentation and public metadata rather than runnable server code. MCP clients connect to `https://verify.sarnai.dev/mcp`. The available MCP operations are `verify_schema`, which maps to the schema verification endpoint, and `get_verification_record`, which retrieves an agent score from the score endpoint.

REST clients can submit verification requests to `/verify/schema` or `/verify/deliverable`. The deliverable route performs the same check under a second name. Agent score lookups use `GET /score/{agent_id}`, while reputation history is available through the separate REST reputation route.

The service uses x402 v2 for paid calls. Payments are made in USDC on Base or Solana, and payment details should be taken from the live x402 manifest or a `Payment-Required` response rather than hard-coded from documentation. Verification failures are valid charged results because the checks still run; malformed requests are rejected before payment.

## Setup and configuration

No local installation, account, or signup is required for the hosted MCP endpoint. Configure an MCP client with the Streamable HTTP URL `https://verify.sarnai.dev/mcp`. The repository does not provide a local process or source package to run.

During the launch period, verification calls share a daily free allowance across MCP and REST for each request IP address. The current limit is published in `/llms.txt`, not fixed in the repository documentation. Responses expose remaining allowance and reset information. Once the allowance is exhausted, verification calls require x402 payment. Score lookups cost $0.01 when a score exists; unknown agents and reserved `test-` identifiers receive a free signed no-data response.

Python users can instead install the official `sarnai` package and call `SarnAIClient.verify_output` with a schema and value. The client raises `PaymentRequiredError` when a verification request requires payment.

## Tools and capabilities

Agent Output Verifier by SarnAI provides:

- `verify_schema` for checking an output against JSON Schema and optional rules.
- `get_verification_record` for retrieving an agent's score record through the score service.
- Pass/fail results, check percentages, and fix hints.
- Signed attestations and receipts using Ed25519, RFC 8785 JSON canonicalization, and SHA-256 hashing.
- REST equivalents for schema and deliverable verification.
- Agent score and reputation endpoints, plus health, discovery-card, x402-manifest, and interactive documentation endpoints.

## Limitations and notes

Agent Output Verifier by SarnAI is a hosted service; this repository cannot be installed as a self-hosted verifier. Free usage is launch-specific and its allowance can change, so clients should inspect `/llms.txt` and live payment responses. MCP and REST verification calls share the same IP-based allowance.

The verifier accepts structured requests and rejects malformed JSON, missing fields, unknown rule types, oversized identifiers, and bodies over the service limit. Errors use HTTP 422 for invalid requests and 413 for bodies that exceed the limit; invalid requests are not charged. Payment is required after the free allowance and for score lookups that have existing data.

Receipts and attestations refer to the service's public verification key and endpoint. The original Render hostname remains available with the same responses and keys, but newly configured clients should use `https://verify.sarnai.dev`.

_Full upstream README: https://allmcps.com/mcp/agent-output-verifier-by-sarnai/readme_