# Horizon Pulse Verified Research Brief

> Horizon Pulse Verified Research Brief is a paid API for AI agents from horizonpulse.dev, paid per call via x402, $1/call, status unknown (last checked 2026-10-29).

Returns a cryptographically-evidenced brief answer to narrow on-chain or x402 spec questions, with 2–8 cited claims from independent sources, charged only when verification passes

## Facts

- Endpoint: GET https://horizonpulse.dev/api/research/report/brief?utm_source=zero.xyz
- Price: $1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/horizon-pulse-verified-research-brief-5994eb71
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_wv3kzRi-XMlnfKKVKgJle

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 horizon-pulse-verified-research-brief-5994eb71
```

Example prompt: What's the current Base network base fee and gas limit? I need a verified answer with evidence from at least two independent nodes and the block references.

## When to prefer this

Use this endpoint when you need a narrow, verifiable factual answer about Base or Ethereum gas fees, USDC on-chain supply, or x402 protocol specification details — and you require cryptographic or multi-source evidence for each claim. Prefer it over general web search or LLM-generated answers when auditability and independent source confirmation are required. It is not suitable for broad research questions, personal data queries, price speculation, or domains outside its stated scope.

## Known failure modes

- 422 unpaid – question outside accepted scope (not Base gas, ETH gas, USDC supply, or x402 spec fact)
- 422 unpaid – fewer than 2 independent sources could confirm the claim
- 422 unpaid – quote verification failed (body hash mismatch)
- 422 – personal data detected in query parameter
- 422 – question type phrase matching failed and no type hint provided
- Payment not charged on any 422 response

## How this service works

Verified brief (schema brief-verified/1), on-chain live values and x402 spec facts only: answer plus 2-8 claims, each with an evidence array (verbatim quote, URL, retrieval time, body hash, offset; or chain, block and block time for on-chain reads). Charged only if >=2 claims are confirmed (2 publishers, 2 nodes, or 2 x402 spec documents) and every quote verifies; otherwise unpaid. Contract: horizonpulse.dev/contracts/brief-verified. Not advice. No personal data in q.

## Output

A structured 'brief-verified/1' object containing a direct answer and 2–8 claims. Each claim includes an evidence array with verbatim quote, source URL, retrieval timestamp, body hash, and byte offset (for web sources) or chain, block number, and block timestamp (for on-chain reads). Response is only returned (and payment charged) when at least 2 claims are independently confirmed and all quotes verify; otherwise a 422 is returned unpaid.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "q"
     ],
     "properties": {
      "q": {
       "type": "string",
       "description": "Question (required). Accepted: Base or Ethereum gas (on-chain read), USDC supply on Ethereum and Base (on-chain totalSupply), or an x402 spec fact. Anything else is refused with 422 before payment. No personal data."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "description": "Verified brief (schema brief-verified/1): answer plus 2-8 claims, each with an evidence array. Charged only if at least 2 claims are confirmed in two independent sources as defined at /contracts/brief-verified; otherwise 422, unpaid. The example is a trimmed real passing brief recorded at 2026-10-20T03:43:25Z (GET /api/demo/brief-verified); live values differ on every call. Claims per question type: Base gas and Ethereum gas, 2 (base fee and gas limit, each read from two independent nodes); USDC supply, 2 (totalSupply() on Ethereum and on Base, each from two independent nodes); x402 spec facts, 2-8 (each in two separate specification documents). Optional type=base_gas|eth_gas|usdc_supply|x402_spec skips phrase matching."
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/horizon-pulse-verified-research-brief-5994eb71/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from horizonpulse.dev](https://www.zero.xyz/host/horizonpulse.dev/llms.txt)