# Verity Suite Ground Pro — Calibrated Q&A with Signed Receipts

> Verity Suite Ground Pro — Calibrated Q&A with Signed Receipts is a paid API for AI agents from suite.veritylayer.dev, paid per call via x402, $0.35/call, status unknown (last checked 2026-09-14).

Answers a natural-language question with a calibrated confidence score, cited sources, caveats, and an optional Ed25519-signed verifiability receipt

## Facts

- Endpoint: POST https://suite.veritylayer.dev/ground/pro
- Price: $0.35/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/verity-suite-ground-pro-calibrated-q-a-with-signed-receipts-2dca1521
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_zKpij3r5MSP-kykDEsnEy

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 verity-suite-ground-pro-calibrated-q-a-with-signed-receipts-2dca1521 -d '<json body>'
```

Example prompt: Is it true that the Eiffel Tower is taller than the Empire State Building? Give me a grounded answer with how confident you are and any caveats I should know about.

## When to prefer this

Choose this endpoint when your agent needs a trustworthy, calibrated answer — not just any plausible response. It is ideal when downstream decisions depend on knowing how confident the answer is, when you need cited sources rather than generated prose, when honest 'I don't know' responses are preferable to hallucination, or when you require a cryptographically signed receipt for audit, compliance, or multi-agent verification chains. Prefer it over raw LLM calls when epistemic honesty and accountability matter more than creative generation.

## Known failure modes

- Empty or blank question field returns a validation error
- Question exceeding 2000 characters is rejected
- Context exceeding 2000 characters is rejected
- If the answer cannot be determined, the answer field states this honestly rather than hallucinating
- Signing not configured results in a null receipt field
- Malformed JSON body or incorrect bodyType causes a 400-class error
- Payment failure or insufficient USDC balance returns a 402 response blocking the call

## How this service works

The trust fabric for AI agents — calibrated, fail-closed services agents pay per call.

## Output

A JSON object containing: a plain-language answer (or an honest statement that the answer cannot be determined), a calibrated confidence score between 0 and 1, an array of actual sources used, an array of caveats (gaps, assumptions, or uncertainties), and optionally an Ed25519-signed VerityLayer receipt for cryptographic verification.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "context": {
   "anyOf": [
    {
     "type": "string",
     "maxLength": 2000
    },
    {
     "type": "null"
    }
   ],
   "title": "Context",
   "default": null,
   "description": "optional context to consider"
  },
  "question": {
   "type": "string",
   "title": "Question",
   "maxLength": 2000,
   "minLength": 1,
   "description": "the question to answer"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/verity-suite-ground-pro-calibrated-q-a-with-signed-receipts-2dca1521/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from suite.veritylayer.dev](https://www.zero.xyz/host/suite.veritylayer.dev/llms.txt)