The client sends a discover request carrying the per-request _meta
(protocolVersion, clientInfo, clientCapabilities), and the server
replies with the protocol versions it supports, its capabilities, and its
identity via `_meta.io.modelcontextprotocol/serverInfo`.

-- client --
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "server/discover",
  "params": {
    "_meta": {
      "io.modelcontextprotocol/protocolVersion": "2026-07-28",
      "io.modelcontextprotocol/clientInfo": { "name": "ExampleClient", "version": "1.0.0" },
      "io.modelcontextprotocol/clientCapabilities": {}
    }
  }
}
-- server --
{
	"jsonrpc": "2.0",
	"id": 1,
	"result": {
		"resultType": "complete",
		"_meta": {
			"io.modelcontextprotocol/serverInfo": {
				"name": "testServer",
				"version": "v1.0.0"
			}
		},
		"ttlMs": 0,
		"cacheScope": "public",
		"supportedVersions": [
			"2026-07-28",
			"2025-11-25",
			"2025-06-18",
			"2025-03-26",
			"2024-11-05"
		],
		"capabilities": {
			"logging": {}
		}
	}
}