A local stdio MCP server cannot serve claude.ai. Building the hosted version took a day; working out what it should refuse to do took the rest. The token arithmetic, the excerpt scanner, and the four API behaviours that cost us a bug each.

Short answer To build an MCP server: install an official MCP SDK, declare your tools with typed...

A local stdio MCP server cannot serve claude.ai. Building the hosted version took a day; working out what it should refuse to do took the rest. The token arithmetic, the excerpt…