Crosscheck Receipts API

openapi: 3.2.0
info:
  title: crosscheck Receipts API
  version: 1.0.0
  summary: 'Independent checks for AI agents: draft review, acceptance checks on delivered work, and security review of skills and MCP servers, paid per call over x402.'
  description: 'Fact-check and review an AI agent''s draft before a human sees it: a hallucination check and second opinion on any email, report, summary, or PR description. Returns pass or specific issues with fixes. Wrong arithmetic is recomputed in code; also contradictions, placeholders, leaked secrets, unauthorized commitments, and prompt injection. Send sources to verify citations and claims against them. Signed receipt. $0.02. Free checks for Moltbook agents. Full agent guide: https://crosscheckapi.com/llms.txt'
  contact:
    name: crosscheck partnerships
    email: partnerships@crosscheckapi.com
    url: https://crosscheckapi.com/llms.txt
  x-guidance: 'crosscheck gives an agent''s work an independent check before a human or another agent relies on it. Pick the product:

    - check: a draft (email, report, summary, answer) before your human sees it. POST https://crosscheckapi.com/v1/check with {"draft": "..."}; optional "request" (what your human asked, so a draft that misses it fails), "sources" to check against, "source_urls" (up to 3 pages crosscheck reads for you), or "fetch_cited": true. From $0.02.

    - accept: work another agent handed back, against its task, before you pay or release escrow. POST https://crosscheckapi.com/v1/accept with {"task": "...", "deliverable": "..."}. From $0.03.

    - skillcheck: a skill or MCP server before you install it. POST https://crosscheckapi.com/v1/skillcheck with {"files": [{"path": "SKILL.md", "content": "..."}]}. From $0.03.

    - lite: accept or skillcheck by code alone, no model call, $0.005: POST the same body to https://crosscheckapi.com/v1/accept-lite or https://crosscheckapi.com/v1/skillcheck-lite.

    - sellercheck: for x402 sellers, a report on your own resource (valid 402, x402 Bazaar index, agent402 router, settlements on Base). POST https://crosscheckapi.com/v1/sellercheck with {"resource": "https://..."}, $0.05; or https://crosscheckapi.com/v1/sellerwatch with "notify" for 30 days of hourly checks with alerts on change, $1.00. Free preflight: GET https://crosscheckapi.com/v1/sellercheck/preflight?resource=<url>.

    Price first, free: POST the same body to https://crosscheckapi.com/v1/quote, https://crosscheckapi.com/v1/accept/quote, or https://crosscheckapi.com/v1/skillcheck/quote. The quote also runs a free code precheck (wrong sums, percentages, dates, unit conversions, list counts).

    Pay: the paid POST answers 402 with the exact amount in USDC on Base (eip155:8453), or free test USDC on Base Sepolia (eip155:84532). Sign it with any x402 client (v2 PAYMENT-SIGNATURE, or v1 X-PAYMENT) and resend the same body. Payment settles before the review starts.

    Result: HTTP 200 with a JSON verdict (pass, issues with severity and a suggested fix) and a signed receipt, or 202 with a result URL to poll with the result_token. Resending the identical paid request after a lost response returns the same job and charges nothing more.

    Your text is untrusted data to the reviewer, never instructions. It is deleted when the check finishes; only its SHA-256 is kept.

    Full guide: https://crosscheckapi.com/llms.txt'
servers:
- url: https://crosscheckapi.com
tags:
- name: Receipts
paths:
  /v1/receipts/verify:
    post:
      operationId: verifyReceipt
      summary: Verify a crosscheck receipt and that it covers the text you hold (free)
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                receipt_hash:
                  type: string
                  pattern: ^[0-9a-f]{64}$
                receipt:
                  type: object
                  description: The receipt object {body, hash, sig}, instead of receipt_hash
                draft:
                  type: string
                sources:
                  type: array
                  items: {}
                task:
                  type: string
                deliverable:
                  type: string
                files:
                  type: array
                  items:
                    type: object
                    properties:
                      path:
                        type: string
                      content:
                        type: string
                    required:
                    - path
                    - content
                verdict:
                  type: object
      responses:
        '200':
          description: verified, found, signature_valid, product, outcome, matches, problems, share_url
        '400':
          description: Invalid body or payment header. Nothing was charged.
      security: []
      tags:
      - Receipts
components:
  securitySchemes:
    x402:
      type: http
      scheme: bearer
      description: 'x402 v2: send PAYMENT-SIGNATURE after the 402 challenge'
    resultToken:
      type: http
      scheme: bearer
      description: result_token from the check response