Build and maintain Model Context Protocol servers using deterministic architecture, atomic tools, strict input validation, structured outputs, and observable execution. Use when creating a new MCP server, adding or refactoring tools, designing tool schemas, adding MCP tests, or preparing an MCP package for publication.
Read agents/shared/mcp-builder-core.md first and apply all constraints.
[domain].tools.ts module per domain.npm run verify before finishing.Do not publish until all are true: