I built an MCP server without the @modelcontextprotocol/sdk — here's what I learned

I shipped a Model Context Protocol server last month. It's live on Anthropic's official registry as io.github.cammac-creator/openswissdata. It exposes nine tools over JSON-RPC 2.0 to any MCP-compatible client (Claude Desktop, Cursor, Cline, you name it). I built it without @modelcontextprotocol/sdk. Not because the SDK is bad — it isn't. But because for my stack, the friction of fitting it in wasn't paid back by any feature I needed. This post is the honest write-up of that decision, the wire...