Screwtape.ai

{
  "name": "Screwtape.ai",
  "description": "Screwtape.ai decides whether an AI agent is allowed to spend money, and keeps the proof. Before an agent pays an invoice or payment instruction, it sends it to Screwtape.ai first. POST /v1/duplicate (MCP tool check_duplicate_invoice) checks it against the invoices that API key already recorded (unique, duplicate, possible_duplicate or replay), runs the rules you pass as checks (line items that must add up to the total, an expected amount, equals, regex, JSON schema, required fields) and judges it against your evidence, such as the purchase order. The answer is pass, fail, or retry with reasons, plus an Ed25519-signed receipt anyone can check at POST /v1/receipts/verify. Pay only on pass. The same verdict covers any other agent output before it is acted on (POST /v1/judge), and POST /v1/consensus flags false consensus when several agents agree. A second check, outside your agent. Screwtape advises and records, does not hold funds, and relies on the agent to cooperate. Screwtape runs as a separate service from your agent, with its own prompt and checks, and it is not paid more when your agent passes. Every verdict comes with a signed receipt you can verify yourself. The receipt proves what was checked, when, and the verdict that was returned. New REST/MCP products: Budget Ledger ($0.002), Action Receipts ($0.003), 3 free calls per UTC day without a key plus 10/day with a free key, shared across HTTP/MCP (anonymous 3/minute and global 2000/day; private daily IP hash). Skills: check_duplicate_invoice (duplicate invoice check before an agent pays; Bearer key or x402 payment), judge (pass/fail/retry verdict on one agent output against your evidence), consensus (false-consensus check across 2 to 16 answers), get_api_key (free key, 10 calls per UTC day, proof of work), publish_receipt. A2A JSON-RPC message/send at https://screwtape.ai/a2a maps to judge (send a duplicate object in the data part to check an invoice). The same skills are on MCP (https://screwtape.ai/mcp) and REST (https://screwtape.ai/openapi.json). After the anonymous allowance, unpaid calls return x402 payment requirements ($0.005 USDC per call on Base or Solana).\n\nAfter the 3/day anonymous allowance, a skill call needs either a Bearer API key (free: POST https://screwtape.ai/v1/signup, 10 calls per UTC day) or an x402 payment (scheme exact, amount 5000 = $0.005 USDC on Base eip155:8453 or Solana). A call with neither after anonymous access is exhausted returns HTTP 402 with the x402 requirements.",
  "url": "https://screwtape.ai/a2a",
  "version": "1.2.2",
  "documentationUrl": "https://screwtape.ai/docs/",
  "capabilities": {
    "streaming": false,
    "pushNotifications": false,
    "extendedAgentCard": false,
    "extensions": [
      {
        "uri": "https://screwtape.ai/ext/x402/v1",
        "description": "Per-call x402 payment. Details in params.",
        "required": false,
        "params": {
          "protocol": "x402",
          "version": 2,
          "discovery": "https://screwtape.ai/.well-known/x402",
          "scheme": "exact",
          "asset": "USDC",
          "productPrices": {
            "budget": "0.002",
            "receipt": "0.003"
          },
          "amount": "5000",
          "perCallUsd": "0.005",
          "paymentHeader": "PAYMENT-SIGNATURE",
          "anonymousFree": {
            "callsPerDay": 3,
            "perMinute": 3,
            "globalPerDay": 2000,
            "identity": "secret-salted daily IP hash; no raw IP stored; daily scope"
          },
          "freeKey": {
            "signup": "POST https://screwtape.ai/v1/signup",
            "callsPerDay": 10
          },
          "networks": [
            {
              "id": "eip155:8453",
              "payTo": "0x028Bb9A57B8C27c22f6B39dd00e7eFF1FB60344B"
            },
            {
              "id": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
              "mint": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
              "payTo": "56cBfPbDrz3DGnGD8xUfkuffYS6qMXqXFfQY3KnE1YpL",
              "payToRole": "owner",
              "offered": true
            }
          ]
        }
      },
      {
        "uri": "https://a2a-registry.org/extensions/registry/v1",
        "description": "Payment discovery: free key tier plus x402 per-call payments.",
        "required": false,
        "params": {
          "payment": {
            "model": "freemium",
            "protocols": [
              "x402"
            ],
            "direction": "inbound",
            "rails": [
              {
                "network": "base",
                "token": "USDC",
                "type": "stablecoin",
                "caip2": "eip155:8453",
                "contractAddress": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
                "protocol": "x402",
                "scheme": "exact"
              },
              {
                "network": "solana",
                "token": "USDC",
                "type": "stablecoin",
                "caip2": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
                "contractAddress": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
                "protocol": "x402",
                "scheme": "exact"
              }
            ]
          }
        }
      }
    ]
  },
  "authentication": {
    "schemes": [
      "bearer",
      "x402"
    ]
  },
  "defaultInputModes": [
    "application/json",
    "text/plain"
  ],
  "defaultOutputModes": [
    "application/json"
  ],
  "skills": [
    {
      "id": "budget_ledger",
      "name": "Budget Ledger",
      "description": "REST POST /v1/budget or MCP budget_ledger. Cumulative USD spend reservations across sub-agents, immutable cap, retry/velocity flags; allow/warn/block. $0.002/call or shared free allowance. Not available through A2A message/send.",
      "inputModes": [
        "application/json"
      ],
      "outputModes": [
        "application/json"
      ],
      "tags": [
        "budget",
        "agents"
      ]
    },
    {
      "id": "action_receipt",
      "name": "Action Receipts",
      "description": "REST POST /v1/receipt or MCP action_receipt. Ed25519 signed, hash-chained action records. $0.003/call or shared free allowance. GET /v1/receipt/verify free. Not available through A2A message/send.",
      "inputModes": [
        "application/json"
      ],
      "outputModes": [
        "application/json"
      ],
      "tags": [
        "receipts",
        "agents"
      ]
    },
    {
      "id": "check_duplicate_invoice",
      "name": "Check an invoice for duplicates before the agent pays",
      "description": "Duplicate invoice check before an agent pays, with a signed receipt. Compares the invoice with the ones this API key recorded earlier and judges it like judge. Input: POST /v1/duplicate, the MCP tool check_duplicate_invoice, or A2A message/send with a data part, sending task, agent_output (the invoice JSON) and duplicate {vendor_path, invoice_id_path, amount_path, currency_path?, date_path?, window_days?, store?}. Output: the judge result plus duplicate.status (unique, duplicate, possible_duplicate, replay or not_checked). Takes a Bearer key or an x402 payment (no key needed); fingerprints are kept per API key, or per paying wallet (the facilitator-verified x402 payer); only keyed HMAC fingerprints are stored, and only when store is true. Cost: same as judge.",
      "inputModes": [
        "application/json"
      ],
      "outputModes": [
        "application/json"
      ],
      "tags": [
        "invoices",
        "duplicates",
        "payments",
        "validation"
      ],
      "examples": [
        "Has this invoice already been paid?",
        "Check this vendor invoice for duplicates before I pay it."
      ]
    },
    {
      "id": "judge",
      "name": "Judge one agent output (pass, fail or retry)",
      "description": "Pass/fail/retry verdict on one agent output, checked against the evidence and criteria you send. Use it before returning or acting on a draft. Not for web lookup or for comparing several answers (use consensus). Input: POST /v1/judge, the MCP tool judge, or A2A message/send, with task and agent_output plus optional evidence[], criteria[] and retain. Output: verdict, score 0 to 1, reasons, engine, request_id, retention. Cost: free key (10 calls per UTC day) or $0.005 USDC per call via x402 on Base or Solana.",
      "inputModes": [
        "application/json"
      ],
      "outputModes": [
        "application/json"
      ],
      "tags": [
        "judge",
        "validation",
        "verdict",
        "x402"
      ],
      "examples": [
        "Check this answer against the evidence before I send it.",
        "Is this agent output supported by these sources?"
      ]
    },
    {
      "id": "consensus",
      "name": "False-consensus check across 2 to 16 agent answers",
      "description": "False-consensus check: scores agreement across 2 to 16 answers to one task and flags agreement that looks copied or thin. Use it before accepting a majority vote. Not for a single answer, and not proof of correctness: verify consensus_answer with judge. Input: POST /v1/consensus, or MCP tool consensus, with task and answers[{agent_id?, output}]. Output: consensus_answer, agreement_score, false_consensus_risk (low, medium or high), reasons, clusters, engine, request_id. Cost: same as judge, on Base or Solana.",
      "inputModes": [
        "application/json"
      ],
      "outputModes": [
        "application/json"
      ],
      "tags": [
        "consensus",
        "false-consensus",
        "x402"
      ],
      "examples": [
        "Five agents agreed. Is that agreement trustworthy?",
        "Score these three answers for false consensus."
      ]
    },
    {
      "id": "get_api_key",
      "name": "Get a free API key (proof of work, no human approval)",
      "description": "Creates a free key (10 calls per UTC day). Use it only when no key exists and you can compute SHA-256 in code. Input: POST /v1/signup, or MCP tool get_api_key, with pow_nonce (SHA-256 of screwtape-signup-v1:<UTC YYYY-MM-DD>:<nonce> must start with 12 zero bits; nonce matches ^[A-Za-z0-9_-]{8,64}$), plus optional email and name (at most 80 characters). Output: api_key (shown once), key metadata, request_id. Limits: 5 keys per IP per hour and per UTC day. Free.",
      "inputModes": [
        "application/json"
      ],
      "outputModes": [
        "application/json"
      ],
      "tags": [
        "signup",
        "api-key"
      ],
      "examples": [
        "Create a free Screwtape key for this agent."
      ]
    },
    {
      "id": "publish_receipt",
      "name": "Publish one signed receipt as a Screwtape Verified badge",
      "description": "Publish a receipt you own so a public page and badge link to that one verdict. It states that this output got this verdict at this time; it is not a general certification of the agent. Input: receipt_id, optional include_content, label, unpublish. Output: public_url, badge_svg_url, embed_html, embed_markdown. Needs the Bearer key that owns the receipt; no x402. Free. Available on MCP and REST.",
      "inputModes": [
        "application/json"
      ],
      "outputModes": [
        "application/json"
      ],
      "tags": [
        "receipt",
        "badge",
        "verification"
      ],
      "examples": [
        "Publish the receipt for this verdict so I can link to it."
      ]
    }
  ],
  "protocolVersion": "0.3.0",
  "preferredTransport": "JSONRPC"
}