{"name":"Countersign by Signalry","description":"Countersign by Signalry: re-runs the checks behind an AI agent's done claim; hash-chained receipts. Reached over MCP (https://countersign.signalry.ai/mcp) and a REST API (https://countersign.signalry.ai/openapi.json); it does not serve A2A message methods. Receipts travel inside A2A tasks through the extension listed under capabilities.","supportedInterfaces":[{"url":"https://countersign.signalry.ai/mcp","protocolBinding":"MCP","protocolVersion":"1.0"},{"url":"https://countersign.signalry.ai/v1","protocolBinding":"HTTP+JSON/REST (OpenAPI 3.1, not A2A methods)","protocolVersion":"1.0"}],"provider":{"organization":"Signalry","url":"https://signalry.ai"},"version":"0.1.0","documentationUrl":"https://countersign.signalry.ai/start","capabilities":{"streaming":false,"pushNotifications":false,"extensions":[{"uri":"https://countersign.signalry.ai/a2a/v1","description":"Countersign receipt references in A2A artifacts, and a keyless counterparty check (POST /v1/a2a/verify).","required":false}]},"securitySchemes":{"bearer":{"httpAuthSecurityScheme":{"scheme":"Bearer","description":"Optional agent key (csk_...). Reads and verification need no key.","bearerFormat":"csk"}}},"defaultInputModes":["application/json"],"defaultOutputModes":["application/json","text/html"],"skills":[{"id":"submit_claim","name":"File and verify a claim","description":"Records a claim with public checks (http, dns, tls_cert, github_pr, git_public), runs them, and returns status, evidence tier, counts_as_verified and a receipt URL.","tags":["verification","receipts","claims"],"examples":["https://example.com serves release notes v2"],"inputModes":["application/json"],"outputModes":["application/json"]},{"id":"get_status","name":"Check a claim","description":"Returns the current status, counts_as_verified, limits and recent receipts for a claim id; no key needed.","tags":["verification","reliance"],"examples":["Status of claim csh-0123456789"],"inputModes":["application/json"],"outputModes":["application/json"]},{"id":"verify_a2a_artifact","name":"Check a counterparty's receipt","description":"Checks a Countersign receipt reference inside an A2A task, message, artifact or part against the live ledger.","tags":["a2a","verification"],"examples":[],"inputModes":["application/json"],"outputModes":["application/json"]}],"iconUrl":"https://countersign.signalry.ai/icon.png"}