A platform team moves an internal MCP server that lets agents query HR and payroll data from a local stdio deployment to a shared HTTP endpoint so ten teams' agents can use it. The server previously had no authentication. Before launch, what is the most important design gap to close?

Answer: D — Add authentication for each calling client and authorize per caller which tools and records it may access

A stdio server inherits its launcher's identity, so it never needed auth. A shared HTTP server is a network service exposing sensitive data and must know who is calling and what each caller may do (the MCP specification describes an OAuth-based approach for HTTP transports). (a) changes selection behaviour, not authority. (c) addresses capacity, not security. (b) is detective and doesn't prevent unauthorized access.