Optional parameters should be made nullable

[laszlo-ratesic]

Is your feature request related to a problem? Please describe.

I have an agent that uses the Stripe MCP server and sometimes passes null to optional parameters, causing the tool call to fail.

Describe the solution you'd like

It would be great if optional parameters could also be marked nullable to prevent these errors.

Describe alternatives you've considered

I've tuned my prompts as much as possible but there always seems to be another parameter I've missed that ends up being optional but not nullable

Additional context

No response

[laszlo-ratesic]

list_customers

create_payment_link

[laszlo-ratesic]

I noticed the zod schema for list_customers uses .optional() (which protects passing undefined) but doesn't also use .nullable() which I think would help. I'm not sure if this would break anything though.

export const listCustomersParameters = (_context: Context = {}) =>
  z.object({
    limit: z
      .number()
      .int()
      .min(1)
      .max(100)
      .optional()
      .describe(
        'A limit on the number of objects to be returned. Limit can range between 1 and 100.'
      ),
    email: z
      .string()
      .optional()
      .describe(
        "A case-sensitive filter on the list based on the customer's email field. The value must be a string."
      ),
  });

[matv-stripe]

Hey @laszlo-ratesic , we will look into this. OOC are you using mcp.stripe.com directly, or this SDK? Can you say more about your integration and what you are building?