# agent-receipts

> Verifiable provenance for autonomous-agent actions — issue a signed, content-hashed, hash-chained receipt for any agent action; verify it later for audit, compliance, and dispute resolution. Built for autonomous AI agents.
> Pay-per-call over the Model Context Protocol using the x402 "Payment Required"
> standard (Coinbase x402, USDC on base). No signup, no API key to read the
> free tiers; pay only for the premium result.

## MCP endpoint

- https://agent-receipts.dropwatchhq.com/mcp  (transport: streamable-http; call tools/list then tools/call)

## Paid tools (x402 pay-per-call, USDC on base)
- `issue_receipt` — $0.01 USDC/call. Mint a signed (ed25519), content-hashed (SHA-256), timestamped, hash-chained provenance receipt for one agent action.

## Free tools
- `verify_receipt` — free. Verify a receipt's authenticity + return its provenance record.
- `list_receipts` — free. List an agent's receipt hash-chain, newest first.

## How an agent pays (x402 over MCP)

1. POST https://agent-receipts.dropwatchhq.com/mcp with JSON-RPC tools/call for a paid tool. The result returns a
   FREE PREVIEW plus an `x402` descriptor inside structuredContent:
   { "x402Version":1, "accepts":[ { "scheme":"exact", "network":"base",
     "maxAmountRequired":"<atomic USDC>", "asset":"<USDC on Base>",
     "payTo":"0x38134a7F97636E26365Fb17405566595B917a341", "extra":{"name":"USD Coin","version":"2"} } ] }
2. Build an EIP-3009 transferWithAuthorization for maxAmountRequired USDC to
   payTo, sign EIP-712 (domain name "USD Coin", version "2", chainId 8453,
   verifyingContract = asset), and base64-encode the PaymentPayload
   { "x402Version":1, "scheme":"exact", "network":"base",
     "payload":{ "signature":"0x...", "authorization":{ from,to,value,validAfter,validBefore,nonce } } }
3. Retry the SAME tools/call with header  X-PAYMENT: <base64 payload>
   -> the full result, plus an X-PAYMENT-RESPONSE header (settlement receipt).

The x402 client SDKs (x402-fetch / x402-axios) automate steps 1-3.

## Payment facts

- Network: base (Base mainnet). Asset: USDC (6 decimals).
- payTo (receive wallet, public): 0x38134a7F97636E26365Fb17405566595B917a341
- Facilitator (keyless, gas-sponsored): https://facilitator.payai.network

## Spec

Implements x402 v1 (scheme "exact", EVM EIP-3009). See
https://github.com/coinbase/x402 and https://docs.x402.org .
Machine descriptor: https://agent-receipts.dropwatchhq.com/.well-known/x402