> MCP discards this lesson, opting for schemaless JSON with optional, non-enforced hints. Actually, MCP uses a normative TypeScript schema (and, from that, an

> MCP discards this lesson, opting for schemaless JSON with optional, non-enforced hints. Actually, MCP uses a normative TypeScript schema (and, from that, an autogenerated JSON Schema) for the protocol itself, and the individual tool calls also are specified with JSON Schema. > Type validation happens at runtime, if at all. That's not a consequence of MCP "opting for schemaless JSON" (which it factually does not), that's, for tool calls, a consequence of MCP being a discovery protocol where the tools, and thus the applicable schemas, are discovered aruntime. If you are using MCP as a way to wire up highly-static components, you can do discovery against the servers once they are wired up, statically build the clients around the defined types, and build your toolchain to raise errors if the discovery responses change in the future. But that's not really the world MCP is built for. Yes, that means that the toolchain needs, if it is concerned about schema enforcement, use and apply the relevant schemas at runtime. So, um, do that?