agents.factstamp.dev

Live 402 challenge

Captured by the enrichment pass, not read just now. Prices can change — always read the 402 the endpoint answers with.

{
  "note": "Two cents a call, settled per call over x402 in USDC on Base. This door accepts no pack code and has no unpaid tier: every call is paid.",
  "paid": true,
  "tool": "probe_claim",
  "about": {
    "body": {
      "kind": "figure|entity|citation|package",
      "claim": "string, 8..500 characters",
      "kind_default": "figure"
    },
    "paid": true,
    "tier": "probe",
    "what": "One small claim, verified against the same primary sources the paid doors read, paid per call and receipted. Unknown is a valid answer; nothing is invented.",
    "route": "POST /probe",
    "example": {
      "kind": "figure",
      "claim": "Australia's cash rate target is 3.60%"
    },
    "network": "Base",
    "payment": "x402 (HTTP 402 with `accepts[]`; send the payment on PAYMENT-SIGNATURE or X-PAYMENT)",
    "receipt": {
      "alg": "HMAC-SHA256",
      "note": "A deterministic keyed signature: the same answer and the same key produce the same signature. The answer also carries the Ed25519 receipt of the door that produced it, which verifies offline against the published key set.",
      "covers": "the answer block, with `receipt` and `paid_with` removed",
      "key_id": "probe-v1",
      "canonicalization": "sorted-key JSON, no whitespace"
    },
    "currency": "USDC",
    "elsewhere": {
      "mcp": "https://agents.factstamp.dev/mcp",
      "note": "This is the 2-cent probe door. The same engine answers full-size claims on the paid doors.",
      "pricing": "https://agents.factstamp.dev/pricing.md",
      "manifest": "https://agents.factstamp.dev/.well-known/x402"
    },
    "paid_only": "There is no unpaid tier anywhere on this service, and no pack code is accepted on this door: no payment, no answer.",
    "price_usd": 0.02,
    "rate_limit": {
      "note": "An abuse ceiling, not an allowance: every call inside it is charged at the same two cents.",
      "window": "UTC day and UTC minute, fixed windows",
      "per_day": 1000,
      "counted_on": "CF-Connecting-IP, hashed; X-Forwarded-For is never read",
      "per_minute": 30
    },
    "body_cap_bytes": 2048,
    "amount_base_units": "20000",
    "one_claim_per_call": true,
    "upstream_timeout_ms": 10000
  },
  "error": "This path sells one small claim for two cents a call and has no unpaid tier: the terms below are the ones a POST is charged against, at this same resource. A GET/HEAD is answered with this quote; send POST with an x402 payment to buy an answer.",
  "kinds": [
    "figure",
    "entity",
    "citation",
    "package"
  ],
  "packs": "https://agents.factstamp.dev/packs",
  "accepts": [
    {
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "extra": {
        "name": "USD Coin",
        "version": "2"
      },
      "payTo": "0xc3bcd24a2b350cc73b8516b2a0539a323b42cc32",
      "amount": "20000",
      "scheme": "exact",
      "network": "eip155:8453",
      "mimeType": "application/json",
      "resource": "https://agents.factstamp.dev/probe",
      "description": "A two-cent probe of the FactStamp engine: one small claim in, one cited answer out, receipted. Send a dated figure, a company name, a DOI/arXiv id or a package@version and get the verdict, the value and the source it rests on with our retrieval time — the same engine and the same sources the full-price doors read. Unknown is a valid answer and nothing is invented. Paid per call in USDC on Base; no pack code and no unpaid tier.",
      "maxAmountRequired": "20000",
      "maxTimeoutSeconds": 300
    }
  ],
  "receipt": {
    "alg": "HMAC-SHA256",
    "key_id": "probe-v1"
  },
  "resource": "https://agents.factstamp.dev/probe",
  "discovery": "https://agents.factstamp.dev/.well-known/x402",
  "price_usd": 0.02,
  "uncharged": "unknown is a valid answer: a call that returns no answer is not charged on a pack.",
  "extensions": {
    "bazaar": {
      "info": {
        "input": {
          "body": {
            "kind": "figure",
            "claim": "Australia's cash rate target is 3.60%"
          },
          "type": "http",
          "method": "POST",
          "bodyType": "application/json"
        },
        "output": {
          "type": "json",
          "example": {
            "kind": "figure",
            "tier": "probe",
            "claim": "Australia's cash rate target is 3.60%",
            "probe": true,
            "value": 3.6,
            "source": {
              "url": "https://www.rba.gov.au/statistics/cash-rate/",
              "name": "Reserve Bank of Australia",
              "licence": null,
              "data_as_of": "2026-08-01",
              "http_status": 200,
              "retrieved_at": "2026-10-22T01:02:03.000Z"
            },
            "receipt": {
              "alg": "HMAC-SHA256",
              "key_id": "probe-v1"
            },
            "unknown": false,
            "verdict": "verified",
            "paid_with": {
              "rail": "x402_pay_per_call",
              "list_price_usd": 0.02
            },
            "retrieved_at": "2026-10-22T01:02:03.000Z",
            "list_price_usd": 0.02,
            "amount_base_units": "20000"
          }
        }
      },
      "schema": {
        "type": "object",
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "required": [
          "input",
          "output"
        ],
        "properties": {
          "input": {
            "type": "object",
            "required": [
              "type",
              "method"
            ],
            "properties": {
              "body": {
                "type": "object"
              },
              "type": {
                "const": "http"
              },
              "method": {
                "const": "POST"
              },
              "bodyType": {
                "const": "application/json"
              }
            },
            "additionalProperties": true
          },
          "output": {
            "type": "object",
            "required": [
              "type",
              "example"
            ],
            "properties": {
              "type": {
                "const": "json"
              },
              "example": {
                "type": "object"
              }
            },
            "additionalProperties": true
          }
        },
        "additionalProperties": false
      }
    }
  },
  "rate_limit": {
    "per": "IP",
    "note": "An abuse ceiling, not an allowance: every call inside it is charged at the same two cents.",
    "per_day": 1000,
    "per_minute": 30
  },
  "x402Version": 2,
  "kind_default": "figure",
  "no_pack_code": "No pack code is accepted on this door: it is per-call x402 only.",
  "what_you_get": "Every answer is dated, names the publisher it cites, and carries a receipt that verifies offline without calling us again.",
  "body_cap_bytes": 2048,
  "sample_answers": "https://agents.factstamp.dev/samples",
  "zero_knowledge": {
    "why": "This door does not sell the zero knowledge option. Its settlement does not run through the gate that can blind a ledger entry, so offering it here would be a promise we could not keep.",
    "where": "https://agents.factstamp.dev/ledger/zero-knowledge",
    "option": "zero_knowledge",
    "sold_at": [
      "/check",
      "/entity-file",
      "/il/entity-file",
      "/ca/entity-file",
      "/sanctions",
      "/vat",
      "/citation",
      "/package",
      "/watch",
      "/watch/portfolio",
      "/bulk"
    ],
    "available": false
  },
  "amount_base_units": "20000",
  "one_claim_per_call": true
}

Accepts

The payment requirements as published to the catalog. Read the live 402 before paying — a price here is a claim, not a quote.

[
  {
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "extra": {
      "name": "USD Coin",
      "version": "2"
    },
    "payTo": "0xc3bcd24a2b350cc73b8516b2a0539a323b42cc32",
    "scheme": "exact",
    "network": "eip155:8453",
    "mimeType": "application/json",
    "resource": "https://agents.factstamp.dev/probe",
    "description": "A two-cent probe of the FactStamp engine: one small claim in, one cited answer out, receipted. Send a dated figure, a company name, a DOI/arXiv id or a package@version and get the verdict, the value …",
    "maxAmountRequired": "20000",
    "maxTimeoutSeconds": 300
  }
]

Provenance

Seen in the source catalog

2026-10-21 19:25Z

Last indexed by Roundhouse

2026-10-23 20:46Z

Last enriched (probe, favicon, geo)

2026-10-23 21:16Z

x402 version

1

Max timeout

300s

Liveness probe

HTTP 402