# SignalHarness Agent Tool Schema Validator

> SignalHarness Agent Tool Schema Validator is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Validates a JSON string representing an agent tool schema and returns warnings, analysis, and evidence about its correctness.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/agent_tool_schema_validate/invoke
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signalharness-agent-tool-schema-validator-8f6ef0e7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_WDXD11NMBN9-79LJmtyJ5

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-agent-tool-schema-validator-8f6ef0e7 -d '<json body>'
```

Example prompt: Can you validate this agent tool schema JSON for me and let me know if there are any warnings or issues: '{"name":"get_weather","description":"Returns current weather","parameters":{"type":"object","properties":{"location":{"type":"string"}},"required":["location"]}}'?

## When to prefer this

Choose this endpoint when you need a lightweight, pay-per-call programmatic check of an agent tool schema JSON before deploying or registering it with an AI framework. It is especially useful in CI/CD pipelines, agent marketplaces, or during iterative development where you want fast, structured feedback on schema correctness without running a full agent loop. Prefer this over manual JSON linting when you need structured warnings and evidence metadata returned in a machine-readable format.

## Known failure modes

- Invalid or non-parseable JSON string in request_json returns a validation error
- request_json exceeding 65536 characters is rejected
- Missing required request_json field causes a schema error
- Malformed tool schema may produce warnings rather than hard errors
- Payment failure on the x402 layer prevents execution entirely

## How this service works

Explore 330 pay-per-call x402 API services and 27 agent-native digital products, with Base USDC pricing, secure Polar checkout, and free discovery.

## Output

Returns a JSON object containing a status field (succeeded/failed), a result object with a list of validation warnings, an analysis_json string with structured findings, and an evidence_scope field indicating the data source. Also includes a full execution receipt with payment details, latency, SHA-256 of the result, and artifact references.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "request_json": {
   "type": "string",
   "maxLength": 65536,
   "minLength": 2
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "warnings": [
    "Verify the caller-supplied data before relying on this result."
   ],
   "service_id": "agent_tool_schema_validate",
   "analysis_json": "{\"example\":\"schema-valid caller-supplied data\"}",
   "evidence_scope": "caller_supplied_data"
  },
  "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": "agent_tool_schema_validate",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "5000",
   "resultSha256": "a838718609a8352d7307b0b84ce4e18c656b080415fdc8688fc066d0aa53b41a",
   "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-agent-tool-schema-validator-8f6ef0e7/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)