# SignalHarness Prompt Template Render & Validate

> SignalHarness Prompt Template Render & Validate is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Renders and validates a prompt template from caller-supplied JSON, returning analysis and any warnings about the rendered result.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/prompt_template_render_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-prompt-template-render-validate-f3d5a578
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_SobiOwFhYADzlnvcSqEnX

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-prompt-template-render-validate-f3d5a578 -d '<json body>'
```

Example prompt: Can you validate and render this prompt template JSON for me to make sure it's well-formed and catch any warnings before I use it in my pipeline: '{"system": "You are a helpful assistant.", "user": "Summarize {{text}}"}'?

## When to prefer this

Choose this endpoint when you need to validate and render a prompt template expressed as JSON before using it in an LLM pipeline or agent workflow, particularly when you want structured warnings and analysis rather than just a parse check. It is especially useful in agentic systems that dynamically generate prompt templates and need a pre-flight validation step to catch issues early.

## Known failure modes

- Invalid or malformed request_json string causes parsing failure
- request_json exceeds 65536 character limit returns error
- Missing required request_json field returns validation error
- Caller-supplied data flagged with warnings rather than hard failure
- Network or payment settlement issues may cause receipt status anomalies

## 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 with a status field ('succeeded'), an analysis_json string containing structured analysis of the rendered template, a list of warnings (e.g. about caller-supplied data reliability), an evidence_scope field, and a full receipt including payment details, latency, service version, and a SHA-256 hash of the result.

## 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": "prompt_template_render_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": "prompt_template_render_validate",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "5000",
   "resultSha256": "f4b52f3c4405d04c04df13f52a8b5abc443a1f21724f5d783ed644a3592363aa",
   "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-prompt-template-render-validate-f3d5a578/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)