I think MCP (or any kind of external API) serves a different purpose than ad-hoc code generation and scripting.

In my view, the MCP should be part of the specification. It should expresses intended actions and/or restrictions while the code generated and executed by the LLM is an implementation detail.

This distinction is completely obvious in some cases such as using an external payment gateway. But let's consider a more borderline case.

Say your database is multi-tenant and every query absolutely must include a tenant_id. Now that doesn't necessarily mean you have to use MCP. It could be some command line tool that requires a tenant_id parameter.

But what you can't do is ask the LLM politely to please include a where clause for the tenant_id in any and all SQL statements it decides to generate. You have to impose some things deterministically and MCP is one way to do that.