Is a claim independently corroborated across multiple unrelated sources, or does it tra…

What it does

Is a claim independently corroborated across multiple unrelated sources, or does it trace back to a single origin? Groups matches by SOURCE (not category) so a caller sees exactly how many independent outlets/agencies back a claim -- a trust signal no single-source competitor can offer, since it requires already owning many independent sources.

Tags: fact-checking · trust-signal · source-verification · claim-checking · multi-source · bazaar

Call contract

Method

POST

Input

json

Output

json

Last paid call

2026-10-08

{
  "claim": "the Federal Reserve raised interest rates"
}

{
  "claim": "the Federal Reserve raised interest rates",
  "corroboration_level": "corroborated",
  "distinct_source_count": 3,
  "sources": [
    {
      "category": "news_events",
      "count": 4,
      "source": "gdelt",
      "top_published_at": "2026-07-19T18:30:00+00:00",
      "top_title": "Fed raises rates by 25bps",
      "top_url": "https://example.com/article"
    }
  ],
  "total_matches": 7
}

Use with an agent

1. Discover. Agents find this listing with GET https://bazaar.saylorinnovations.com/discovery/search?query=…, the MCP tool search_resources, or /discovery/resources.
2. Inspect. Fetch /resources/27259.json for the price and payment options.
3. Pay. Call GET https://concordancehq.duckdns.org/tools/corroboration. The provider answers 402 with its payment requirements. An x402 client signs one of the options below and retries with PAYMENT-SIGNATURE.
4. Execute. The provider returns 200 with the data. Agent Bazaar is not in the request path and never sees your payment.

For humans

You don't need an account or an API key; you need a wallet holding a small amount of USDC on Base, Solana, and an x402-capable client (see the examples below). Call the endpoint unpaid first to see exactly what it asks for.

Pricing & payment

Price

$0.04 / request

Protocol

x402 v2

Auth

No account or API key. Pay per request.

Networks

Base, Solana

Demand

2 calls · 2 unique payers in 30d (public x402 Bazaar data)

x402 payment requirements

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0x1f5f8474fA0dc1Fde79187abd68Ef8Ea15ADAe34",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "40000",
    "amountUsd": 0.04,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "payTo": "yEx9WBP1NnzoTpDmi67F536bso3YNcQPBRhWRoswTBS",
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "amount": "40000",
    "amountUsd": 0.04,
    "maxTimeoutSeconds": 300
  }
]

Schemas

{
  "properties": {
    "example": {
      "type": "object"
    },
    "type": {
      "type": "string"
    }
  },
  "required": [
    "type"
  ],
  "type": "object"
}

{
  "example": {},
  "type": "string"
}

Examples

curl -X POST 'https://concordancehq.duckdns.org/tools/corroboration' -H 'Content-Type: application/json' --data '{"claim":"the Federal Reserve raised interest rates"}'
# -> 402 Payment Required; read PAYMENT-REQUIRED
# retry the identical request with PAYMENT-SIGNATURE

const res = await fetch("https://concordancehq.duckdns.org/tools/corroboration", {
  "method": "POST",
  "headers": {
    "content-type": "application/json"
  },
  "body": "{\"claim\":\"the Federal Reserve raised interest rates\"}"
});
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}

import httpx
import json
res = httpx.request("POST", "https://concordancehq.duckdns.org/tools/corroboration", json=json.loads("{\"claim\":\"the Federal Reserve raised interest rates\"}"))
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header

Details

Provider

concordancehq.duckdns.org

Endpoint

https://concordancehq.duckdns.org/tools/corroboration

Machine-readable

/resources/27259.json