---
skill_id: esp-claim-verifier
evaluation: free
price_usd_full: 0.15
challenge: https://lvlltd.com/api/pay?skill=esp-claim-verifier
outline: https://lvlltd.com/skills/esp-claim-verifier/outline.json
standards: x402, ERC-7857
---

# Free sample — ESP Claim Verifier

**Skill ID:** `esp-claim-verifier`  
**Full unlock:** $0.15 USDC via x402 on Base  
**Challenge:** https://lvlltd.com/api/pay?skill=esp-claim-verifier  
**Outline JSON:** https://lvlltd.com/skills/esp-claim-verifier/outline.json

## Summary

Verify factual claims against cited sources and public proof refs. Reject invented metrics. Free-eval first.

## When to use

- Agent brief cites unlocks or volume without proof URLs
- Need anti-hallucination gate before shipping
- Cross-check txHash / ledger rows

## Decision criteria (buy vs skip)

- You need this when: Agent brief cites unlocks or volume without proof URLs
- You get capability: Claim extraction
- Budget fits: full unlock is $0.15 USDC on Base
- You can automate unlock via HTTP 402 without a browser
- You only need teaser/outline first — sealed src/ops stay locked until payment

## Outline (preview)

1. Extract claims that imply success or metrics
2. Require public proof URL or tx for commerce claims
3. Check citation reachability when provided
4. Flag invented counts (null quality is honest)
5. Emit verified | contradicted | unsupported

## Capabilities (preview)

- Claim extraction
- Proof ledger cross-check pattern
- Unsupported claim flags
- Honest null for zero-evidence metrics

## What you get after payment

- SKILL.md (teaser public)
- agent-install.json (public meta)
- src/index.js (stub public; full after unlock)
- Full sealed: src/, schemas/, ops/* (when present) after verified X-PAYMENT

## Agent buy path (zero human UI)

```
GET  https://lvlltd.com/skills/esp-claim-verifier/outline.json
GET  https://lvlltd.com/api/pay?skill=esp-claim-verifier   → HTTP 402
# transfer maxAmountRequired USDC to payTo on Base
POST https://lvlltd.com/api/pay
  X-PAYMENT: {"txHash":"0x…","skill":"esp-claim-verifier"}
# response.sealed_pack.files = full pack
```

## Sample excerpt

# ESP Claim Verifier

**Price:** $0.15 USDC  
**Category:** Trust  
**Version:** 1.0.0  
**Protocols:** x402, ERC-7857  
**Tags:** esp, esp-judge, verifier, x402, evaluator, p1, anti-hallucination, depth:outline_only, demoted-default  

## Summary

Verify factual claims against cited sources and public proof refs. Reject invented metrics. Free-eval first.

## Description

ESP verifier skill for claim-level checks before settle or after sealed delivery.

## When to use

- Agent brief cites unlocks or volume without proof URLs
- Need anti-hallucination gate before shipping
- Cross-check txHash / ledger rows

## After purchase (lvlltd.com)

1. Pay USDC on Base via x402 to the treasury
2. POST `/api/pay` with `X-PAYMENT: {"txHash","skill":"esp-claim-verifier"}`
3. Receive `sealed_pack.files` (code + docs)
4. Install: `node scripts/install-unlocked-pack.mjs unlock.json ./skills`
5. `import { createSkill } from './skills/esp-claim-verifier/src/index.js'`

## Standards

- x402 micropayments (Base USDC / USDbC)
- ERC-7857 sealed iNFT ownership record (marketplace unlock ≠ runtime design)
- Operational packages ship as sealed pack files after verified payment

## Safety

- No secrets, private keys, or exploit content
- Human escalate on high blast-radius actions
- Not legal, tax, medical, or financial advice