Scaffold an MCP server

The five layers

Every MCP server, regardless of target software, has the same skeleton:

1. Server & Transport (src/index.ts) — stdio entry point, lifecycle, cleanup.
2. Tool Definitions (src/tool-definitions.ts) — the contract the AI reads to decide what to call. The single most important file.
3. Router & Handlers (src/tool-router.ts, src/handlers/*.ts) — request dispatch, validation, response shaping.
4. The Bridge (src/executor.ts, scripts/*) — how you actually talk to the target. 80% of the work.
5. Security & Validation (src/utils.ts) — path checks, execFile over exec, tool filtering.

Step 1: Identify the bridge — this decides everything else

Ask: how does the target software let me automate it?