MCP server code conventions

The Python inside a stdio-transport MCP server. Split out of python-conventions-taudelta on 2026-08-31, which keeps the general design defaults — this skill owns only what is different because the code is an MCP server, and those differences are not stylistic: two of the three are protocol correctness.

Not about shipping. Entry points, uv tool install, claude mcp add and scope selection belong to mcp-server-shipping; this is what the code does once it runs.

MCP-stdio logging discipline

Scope: stdio-transport MCP servers only (the *-polite-mcp family) — not applicable to a repo that has no MCP server of its own.