{"service":"receipts","description":"Verifiable action receipts for AI agents. An agent signs a claim about an action with its own key; an independent witness timestamps and countersigns it; anyone can verify the receipt offline using the witness public key.","format":"receipts.v0","status":"beta","pricing":"free","proves":"Agent K asserted action A over content-digest D at time T, independently witnessed at T', and unaltered since. With an anchor, the witness also confirms the real-world effect (email Message-ID, payment txn, or EHR record).","witness_key":{"key_id":"zNo0zXMkkRwNUbNqtHj6diky8Nd9SvMZ8i7m6F99oFE","public_key":{"kty":"OKP","crv":"Ed25519","x":"oKDkj9ODRDR8ASpYs8pKALb0AnwS6u1j7WyivK9UpM4"},"alg":"Ed25519"},"endpoints":{"issue_receipt":{"method":"POST","path":"/receipts","body":{"claim":"Claim","agent_sig":"base64url Ed25519 over the JCS-canonical claim"},"returns":"Receipt (201)","note":"Sign the claim locally with your own key, then POST. Your private key never leaves you."},"get_receipt":{"method":"GET","path":"/receipts/{id}","returns":"Receipt"},"verify":{"method":"POST","path":"/verify","body":"Receipt","returns":"VerifyResult"},"public_key":{"method":"GET","path":"/public-key"},"health":{"method":"GET","path":"/healthz"}},"mcp":{"url":"https://witness.medtekki.no/mcp","transport":"streamable-http","tools":["verify_receipt","get_receipt","service_info"],"note":"Issuance requires client-side signing, so it is NOT exposed over the hosted MCP — issue with the Receipts SDK locally. The hosted MCP offers verify/get."},"verify_offline":"Recompute the JCS-canonical claim, check id == base64url(sha256(claim)), verify agent_sig with receipt.agent.public_key, and verify witness.witness_sig with this witness_key. The reference verifier is open source.","links":{"openapi":"https://witness.medtekki.no/openapi.json","llms_txt":"https://witness.medtekki.no/llms.txt","manifest":"https://witness.medtekki.no/.well-known/receipts.json","terms":"https://witness.medtekki.no/terms","privacy":"https://witness.medtekki.no/privacy"}}