# JSON Contract Check

> JSON Contract Check is a paid API for AI agents from agent-json-reliability.onrender.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-30).

Validates a JSON payload against a contract or schema definition, returning a pass/fail result for AI agent reliability workflows

## Facts

- Endpoint: POST https://agent-json-reliability.onrender.com/v1/json/contract-check?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/json-contract-check-63e1bdac
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_KMDap76YoTsFnKSeW8LTy

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability json-contract-check-63e1bdac -d '<json body>'
```

Example prompt: Can you check whether this JSON payload conforms to the expected contract schema before I send it to the downstream service? The payload is {"name":"Alice","age":30} and the schema requires name as a string and age as a number.

## When to prefer this

Choose this endpoint when you need deterministic, programmatic JSON contract validation as part of an AI agent pipeline — especially when you want to catch schema violations before passing structured data to downstream services. Prefer it over manual inspection or LLM-based validation when you need reliable, repeatable results with a clear pass/fail signal.

## Known failure modes

- Malformed input JSON causes parsing error and validation cannot proceed
- Schema definition is invalid or missing, returning an error
- Payload structure wildly deviates from contract causing verbose error output
- Service unavailable on Render cold start, resulting in timeout
- Payment not processed correctly via x402, blocking the request

## How this service works

Deterministic JSON repair and JSON Schema validation for AI agents. Free MCP, inspect, validate, repair. Paid POST /v1/json/reliable 0.003 USDC via x402 on Base.

## Output

Returns a JSON object with an 'ok' boolean indicating whether the payload passed contract validation, potentially with error details describing schema violations if validation fails.

## Response schema (JSON Schema)

```json
{
 "example": {
  "ok": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/json-contract-check-63e1bdac/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-json-reliability.onrender.com](https://www.zero.xyz/host/agent-json-reliability.onrender.com/llms.txt)