---
name: claim-evaluator
description: Fact-check a single factual claim via Claim Evaluator — returns likelihood 0–100, short reasoning, and 3–5 web sources with stance. Pay per request with AgentCash (Tempo MPP or Base x402) or Stripe Link. Use when the user wants a sourced truth estimate on a checkable claim.
---

# Claim Evaluator

Read fully before acting. Base URL: `https://claim-evaluator.com`

Use this guide for the workflow. Use `https://claim-evaluator.com/openapi.json` for exact schemas and `x-payment-info`.

## When to use

- User asks whether a **factual claim** is true, wants a likelihood, or needs sources.
- Prefer concrete, checkable statements (dates, science, history, public facts).
- Skip opinions, forecasts, and requests that need original research beyond web search.

## Price

- **Tempo USDC (AgentCash / MPP):** about **$0.05** per `POST /v1/evaluate` — live primary crypto rail
- **Base USDC (AgentCash / x402):** about **$0.05** — use only if `/openapi.json` lists an `x402` protocol
- **Stripe SPT (Link CLI):** **$0.50** minimum (card / Link) — same endpoint, different rail

Pay only when calling the paid evaluate route. Discovery routes are free.

## Setup (AgentCash)

1. Ensure a funded AgentCash wallet. For Tempo MPP, bridge/fund **Tempo** USDC:

```bash
npx agentcash accounts
# If you only have Base USDC:
npx agentcash bridge --from base --to tempo --amount 2
```

2. Prefer AgentCash over raw curl — it handles the `402` challenge.

## Evaluate a claim (recommended: Tempo MPP)

1. Confirm the claim text with the user if ambiguous. Keep it one factual statement.
2. Call:

```bash
npx agentcash fetch https://claim-evaluator.com/v1/evaluate \
  -m POST \
  -b '{"claim":"<factual claim>"}' \
  -H "content-type: application/json" \
  --payment-protocol mpp \
  --payment-network tempo \
  --max-amount 1 \
  --timeout 120000
```

**Important:** default AgentCash timeout (30s) is often too short. Payment + web search regularly needs `--timeout 120000`.

3. Success is HTTP 200 JSON:

```json
{
  "likelihood": 0,
  "reasoning": "...",
  "sources": [
    { "name": "...", "url": "...", "stance": "confirm|deny|unclear", "summary": "..." }
  ]
}
```

4. Present likelihood, a short summary of reasoning, and the sources (name + URL + stance). Do not invent sources.

## Base x402 alternative

Only when OpenAPI `x-payment-info.protocols` includes `x402` (and you have Base USDC):

```bash
npx agentcash fetch https://claim-evaluator.com/v1/evaluate \
  -m POST \
  -b '{"claim":"<factual claim>"}' \
  -H "content-type: application/json" \
  --payment-protocol x402 \
  --payment-network base \
  --max-amount 1 \
  --timeout 120000
```

## Stripe Link alternative

If the user prefers card / Link instead of crypto:

```bash
npx @stripe/link-cli mpp pay https://claim-evaluator.com/v1/evaluate \
  -X POST \
  -H "content-type: application/json" \
  -d '{"claim":"<factual claim>"}' \
  --context "<why you are paying; min 100 characters>"
```

## Free helpers

- `GET /openapi.json` — discovery + schemas
- `GET /examples` — sample evaluations
- `GET /llms.txt` — short machine summary
- `GET /health` — liveness