# Freshness / Claim Verifier

> Freshness / Claim Verifier is a paid API for AI agents from mcp.dropenginehq.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-02).

Verifies a factual claim against fresh web evidence within a specified recency window, optionally scoped to preferred domains.

## Facts

- Endpoint: POST https://mcp.dropenginehq.com/api/verify-claim?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/freshness-claim-verifier-9831ac8e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_psBvkJWuk_OO7q09BVxyb

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 freshness-claim-verifier-9831ac8e -d '<json body>'
```

Example prompt: Can you fact-check this claim for me: 'Elon Musk is currently the CEO of Tesla' — check against web sources from the last 30 days, and focus on results from reuters.com and bloomberg.com?

## When to prefer this

Choose this endpoint when you need to ground-truth a specific factual claim against real, recent web evidence — especially when recency matters (e.g., claims about current events, prices, leadership, regulations, or statistics). It is preferable to static knowledge bases or LLM memory when the claim may have changed recently. Use it over general web search when you need a structured verification verdict rather than raw search results. The domain filtering option makes it ideal when you want verification scoped to authoritative or trusted sources only.

## Known failure modes

- Claim text is too short (under 8 characters) or too long (over 2000 characters) — returns validation error
- freshness_days out of range (below 1 or above 3650) — returns validation error
- No fresh web evidence found within the specified freshness window — returns unverified result
- Preferred domain(s) have no indexed or accessible content — reduced evidence coverage
- Ambiguous or highly contested claims may return low-confidence or inconclusive results
- Payment failure (insufficient USDC balance or x402 protocol error) — returns 402 Payment Required
- Network timeout or upstream search service unavailability — returns 503 or timeout error

## How this service works

Verify a factual claim against fresh web evidence.

## Output

Returns a verification result indicating whether the claim is supported, refuted, or unverified by fresh web evidence, along with supporting source URLs, evidence snippets, and a confidence or freshness assessment tied to the specified recency window.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "claim": {
   "type": "string",
   "maxLength": 2000,
   "minLength": 8
  },
  "freshness_days": {
   "type": "integer",
   "maximum": 3650,
   "minimum": 1
  },
  "preferred_domains": {
   "type": "array",
   "items": {
    "type": "string",
    "pattern": "^[a-zA-Z0-9.-]+$",
    "maxLength": 253,
    "minLength": 1
   },
   "maxItems": 10
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/freshness-claim-verifier-9831ac8e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mcp.dropenginehq.com](https://www.zero.xyz/host/mcp.dropenginehq.com/llms.txt)