What MCP Actually Is (Architecture Diagram & Stdio vs. Streamable HTTP)

The Mental Model: JSON-RPC 2.0 Across Process and Edge Boundaries

Every conference talk mentions MCP, yet most tutorials stop at a local Stdio script that only runs on your laptop. In production, remote agents connect over Streamable HTTP at the edge.

export interface JsonRpcRequest {
  jsonrpc: "2.0";
  id: string | number;
  method: "initialize" | "tools/list" | "tools/call";
  params?: Record<string, unknown>;
}

export function createMcpResponse(id: string | number, result: unknown) {
  return Response.json({ jsonrpc: "2.0", id, result });
}

Production Architecture Takeaway

Use Stdio strictly for local CLI tools that need filesystem access. Use Streamable HTTP on Cloudflare Workers for remote multi-tenant agent tools.