Throw bespoke error on incorrectly defined schemas with "z.string().describe()"

[PaulRBerg]

I used an LLM to vibe code my first MCP Framework, and the LLM defined the schema like so:

schema = {
    repository: z.string().describe("Repository name, e.g., 'lockup'"),
  };

Then, I was getting this bug when running the MCP server: #120

The LLM was unable to figure out why it was not working.

The issue was that I had defined the schema like so:

schema = {
  repository: z.string().describe("Repository name, e.g., 'lockup'"),
};

When I should have defined it like so:

schema = {
  repository: {
    description: "Repository name, e.g., 'lockup'",
    type: z.string(),
  },
};

This is something that can be caught at compile time. A bespoke error can be thrown.