[v2] Should raise error at build time if zod outputSchema is not consistent with the structuredContent type

What happened?

I created a tool that outputs a structured content like:

  server.registerTool(
    'ping',
    {
      description: 'Returns a string pong with a timestamp',
      outputSchema: z.object({data: z.string()}) // <---- Wrong return type, should be simply z.string()!
    },
    async () => {
      const str = `Pong at ${new Date()}`
      return {
        content: [{ type: 'text', text: str }], // It seems to be added automatically by the library, but typescript complains if only structuredContent is present
        structuredContent: str
      };
    }
  );

Using only static analysis, we can directly see that this won't work, since outputSchema expects an object but structuredContent outputs a string… and indeed, at runtime this produces an error. Yet, I'd love this kind of error to be catched at build time, with a proper Typescript error.

What did you expect?

An error.

Code to reproduce

  server.registerTool(
    'ping',
    {
      description: 'Returns a string pong with a timestamp',
      outputSchema: z.object({data: z.string()}) // <---- Wrong return type, should be simply z.string()!
    },
    async () => {
      const str = `Pong at ${new Date()}`
      return {
        content: [{ type: 'text', text: str }], // It seems to be added automatically by the library, but typescript complains if only structuredContent is present
        structuredContent: str
      };
    }
  );

SDK version

2.0.0

Area

Server

Start at the server.registerTool entry point and trace how outputSchema and structuredContent are typed and validated in the TypeScript SDK. Reproduce the shown mismatch, then inspect nearby type definitions and existing checks to determine how valid structured outputs are represented. Done means this mismatch produces a TypeScript error at build time without breaking valid tool registrations.