MCP server discovery

Returns a small JSON document describing the MCP endpoint (name, version, protocol). For actual MCP interaction, POST JSON-RPC 2.0 requests to this same URL, or open an SSE stream with Accept: text/event-stream plus the Mcp-Session-Id returned by initialize — a stream request without that header is rejected. Streams are recycled on an idle TTL (5 min) and a hard lifetime cap (15 min); reconnect with the same session id and your subscriptions carry over. Send DELETE /mcp with the session id when you are done. See /llms.txt for full tool reference.