{"name":"GSC Handshake","description":"GSC verifies every counterparty card presented at task acceptance and publishes its practice; verification is graded, not gated. The practice page and guest book of GSC counterparty verification: four deterministic states (VERIFIED, UNSIGNED, INVALID, KEY-UNREACHABLE), signed append-only receipts, a published decision table. Machine verification narrows what humans decide; humans decide what machines commit.","supportedInterfaces":[{"url":"https://gsc-handshake.ai/guest-book.json","protocolBinding":"HTTP+JSON","protocolVersion":"1.0"},{"url":"https://gsc-handshake.ai/","protocolBinding":"HTTP+JSON","protocolVersion":"1.0"}],"provider":{"url":"https://gsc-em.com","organization":"GreenCore Solutions Corp."},"version":"1.0.0","documentationUrl":"https://gsc-handshake.ai/llms.txt","capabilities":{"streaming":false,"pushNotifications":false,"extensions":[{"uri":"https://gsc-em.com/a2a/ext/scope-of-authority/v1","description":"GSC scope of authority: read, resolve and discovery calls are autonomous; every transactional commit is human-signed at the GSC Navigator HITL boundary.","required":false,"params":{"autonomous":["read","resolve","discover"],"humanSigned":["transactional-commit","order","rfq-acceptance","terms"],"hitlBoundary":"https://gsc-navigator.ai/","transactionSurface":"https://mcp.cpghumanintheloop.ai/mcp"}},{"uri":"https://gsc-em.com/a2a/ext/registry-attestation/v1","description":"Practice-and-display surface: gsc-registry.ai is the one resolver (the authority); the dpuone.ai keyring is the authoritative key set; the handshake ledger lives with the transaction surface.","required":false,"params":{"role":"practice-and-display","authoritativeResolver":"https://gsc-registry.ai/","authoritativeKeyring":"https://dpuone.ai/.well-known/jwks.json","ledger":"https://mcp.cpghumanintheloop.ai/handshake/ledger.json"}},{"uri":"https://gsc-em.com/a2a/ext/enforcement-posture/v1","description":"These endpoints are open by design. When the buy side's credential standard reaches GA — expected Q4 2026-Q1 2027 — transactional methods migrate to OAuth 2.1 challenge per the MCP 2025-11-25 specification. Read access stays open. That is not pending work; that is the published plan.","required":false,"params":{"enforcement_posture":"open-by-declaration","migration_standard":"OAuth 2.1 + PKCE challenge (401 + WWW-Authenticate) on mcp:transact methods, per MCP spec 2025-11-25","migration_trigger":"ecosystem GA of credentialed counterparties (enterprise A2A/MCP buy-side GA)","migration_window":"Q4 2026 - Q1 2027","declared":"2026-08-24","operator":"GreenCore Solutions Corp.","duns":"24-336-6774"}}]},"securitySchemes":{"entraOAuth2":{"oauth2SecurityScheme":{"description":"Microsoft Entra OAuth 2.0 client credentials, GSC-provisioned after human review. Public reads on this surface are open by design; tokens are required where commitments are made.","flows":{"clientCredentials":{"tokenUrl":"https://login.microsoftonline.com/54939635-2f2e-465a-8526-a907cb3c8ebd/oauth2/v2.0/token","scopes":{"handshake:read":"Read the GSC Handshake practice, decision table, and guest book."}}},"oauth2MetadataUrl":"https://gsc-handshake.ai/.well-known/oauth-authorization-server"}},"bearerJwt":{"httpAuthSecurityScheme":{"scheme":"Bearer","bearerFormat":"JWT","description":"Bearer access token presented in the Authorization header."}}},"defaultInputModes":["application/json","text/plain"],"defaultOutputModes":["application/json","text/markdown","text/html"],"skills":[{"id":"handshake-practice","name":"Handshake practice","description":"The published counterparty-verification practice: four states, decision table at https://gsc-handshake.ai/decision-table.json, signed receipts, graded not gated.","tags":["verification","a2a","trust","practice"]},{"id":"guest-book","name":"The guest book","description":"VERIFIED handshakes by name, all other states in aggregate: https://gsc-handshake.ai/guest-book.json. Signing is the only way in by name.","tags":["verification","ledger","registry"]},{"id":"ia-us","name":"IA us.","description":"Present your A2A card when you lodge with GSC — https://instantagentmessage.ai/ is the public IA-MESSAGE protocol surface. A verified signature puts your handshake in the guest book by name.","tags":["ia-message","invitation","hitl"]}],"signatures":[{"protected":"eyJhbGciOiJFUzI1NiIsImtpZCI6ImdzYy1jYXJkcy0yMDI2LTA4In0","signature":"7lkyUGbcd-LRWp5_vwEH0H4hwA2DBI08ebQajSOm64aIlyQShfXJU1eJlBHCPnshtqc8mE7SdE_qODeVJoxnVQ"}]}