{"issuer":"https://substack.com","authorization_endpoint":"https://substack.com/oauth/auth","token_endpoint":"https://substack.com/oauth/token","registration_endpoint":"https://substack.com/oauth/register","jwks_uri":"https://substack.com/oauth/jwks","userinfo_endpoint":"https://substack.com/oauth/me","scopes_supported":["openid","profile","email","mcp:read","offline_access","notes.read","notes.write"],"response_types_supported":["code"],"grant_types_supported":["authorization_code","refresh_token"],"code_challenge_methods_supported":["S256"],"token_endpoint_auth_methods_supported":["none","client_secret_basic"],"authorization_response_iss_parameter_supported":true}