# SignalHarness JSON Schema Validate

> SignalHarness JSON Schema Validate is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).

Validates a JSON value against a provided JSON Schema, returning validity status, errors, and failing paths.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/json_schema_validate/invoke
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signalharness-json-schema-validate-4912333e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_F7Gi4LNa2jih5Y-1ZTgYH

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 signalharness-json-schema-validate-4912333e -d '<json body>'
```

Example prompt: Can you validate this JSON object against my schema and tell me exactly which fields are invalid and why? Here's the value: {"name": "Alice", "age": "thirty"} and the schema: {"type": "object", "properties": {"name": {"type": "string"}, "age": {"type": "number"}}, "required": ["name", "age"]}.

## When to prefer this

Choose this endpoint when you need a fast, pay-per-call JSON Schema validation service without managing your own validator infrastructure. It is ideal for agents that dynamically receive JSON values and schemas at runtime and need validation decisions in-line. Prefer this over embedding a local validator library when running in constrained environments or when you want an auditable, receipted validation result with a tamper-evident SHA-256 hash.

## Known failure modes

- Malformed or unparseable JSON in the value field returns an error
- Invalid or unsupported JSON Schema draft version may produce unexpected results
- Very large or deeply nested documents may hit size limits
- Network or payment processing failures result in a non-succeeded status in the receipt
- Boolean schema edge cases (true/false schemas) may not behave as expected on all validators

## How this service works

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## Output

Returns a result object containing a 'valid' boolean, an array of error messages, schema paths that were evaluated, and failing paths pointing to the specific locations in the JSON where validation broke down. Also includes a payment receipt with execution metadata, latency, and a SHA-256 hash of the result for auditability.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "value": {
   "type": [
    "object",
    "array",
    "string",
    "number",
    "boolean",
    "null"
   ],
   "description": "The bounded JSON value to validate."
  },
  "schema": {
   "type": [
    "object",
    "boolean"
   ],
   "description": "The bounded JSON Schema object or boolean schema."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "valid": false,
   "errors": [
    {
     "keyword": "example",
     "message": "example",
     "paramsJson": "example",
     "schemaPath": "example",
     "instancePath": "example"
    }
   ],
   "schemaPaths": [
    "example"
   ],
   "failingPaths": [
    "example"
   ]
  },
  "status": "succeeded",
  "receipt": {
   "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
   "usage": [],
   "status": "succeeded",
   "network": "eip155:8453",
   "artifacts": [],
   "endedAtMs": 0,
   "latencyMs": 0,
   "paymentId": "example-payment",
   "receiptId": "example-receipt",
   "requestId": "example-request",
   "serviceId": "json_schema_validate",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "5000",
   "resultSha256": "372d9dab8e103a1ba952f0bb57c18723365bf22f64adf5cc7c2d5e5f9c9923c4",
   "serviceVersion": "1.0.0",
   "settlementReference": "0x0000000000000000000000000000000000000000000000000000000000000000"
  },
  "artifacts": [],
  "requestId": "example-request",
  "executionId": "example-execution"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/signalharness-json-schema-validate-4912333e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from signalharness.ai](https://www.zero.xyz/host/signalharness.ai/llms.txt)