{
  "protocolVersion": "0.3.0",
  "name": "USERNAME.md Identity Registry",
  "description": "Handle registry and identity anchor for the Agentic Web. Resolves and verifies username.md handles: content-negotiated profiles, did:web documents, signed claims, and per-handle A2A AgentCards. Descriptive discovery surface — task exchange happens over the MCP server and HTTP API, not an A2A JSON-RPC endpoint.",
  "url": "https://username.md/",
  "preferredTransport": "HTTP+JSON",
  "additionalInterfaces": [
    { "url": "https://username.md/", "transport": "HTTP+JSON" }
  ],
  "x-mcp": "https://mcp.username.md/mcp",
  "provider": {
    "organization": "The Holding Company",
    "url": "https://holdingco.com/"
  },
  "iconUrl": "https://username.md/assets/og/index.png",
  "version": "1",
  "documentationUrl": "https://username.md/developers.html",
  "capabilities": {
    "streaming": false,
    "pushNotifications": false,
    "stateTransitionHistory": false
  },
  "security": [],
  "defaultInputModes": ["text/plain", "application/json"],
  "defaultOutputModes": ["text/plain", "application/json"],
  "skills": [
    {
      "id": "resolve-handle",
      "name": "Resolve a handle",
      "description": "GET https://username.md/users/{handle} — content-negotiated identity document (markdown, json, jsonld, jws). Also exposed as the resolve_handle tool on the MCP server at https://mcp.username.md/mcp.",
      "tags": ["identity", "lookup"]
    },
    {
      "id": "verify-handle",
      "name": "Verify a handle",
      "description": "Verify a handle's signatures and did:web document. GET https://{handle}.username.md/.well-known/did.json; verify_handle tool on the MCP server.",
      "tags": ["identity", "verification"]
    },
    {
      "id": "agent-card-lookup",
      "name": "Per-handle AgentCards",
      "description": "Every handle serves its own signed A2A AgentCard at https://{handle}.username.md/.well-known/agent-card.json, with a detached JWS chained to the handle's did:web key.",
      "tags": ["identity", "a2a", "discovery"]
    }
  ],
  "supportsAuthenticatedExtendedCard": false,
  "x-family": {
    "for_users": "https://username.md",
    "for_people": "https://about-me.md",
    "for_agents": "https://finger.md",
    "for_preferences": "https://preferences.sh"
  },
  "x-more": "https://username.md/a2a.html"
}