Function isSimpleStringZodSchema

Determines if the provided Zod schema should be treated as a simple string schema that maps to DynamicTool. This aligns with the type-level constraint of InteropZodType<string | undefined> which only matches basic string schemas. If the provided schema is just z.string(), we can make the determination that the tool is just a generic string tool that doesn't require any input validation.

This function only returns true for basic ZodString schemas, including:

• Basic string schemas (z.string())
• String schemas with validations (z.string().min(1), z.string().email(), etc.)

This function returns false for everything else, including:

• String schemas with defaults (z.string().default("value"))
• Branded string schemas (z.string().brand<"UserId">())
• String schemas with catch operations (z.string().catch("default"))
• Optional/nullable string schemas (z.string().optional())
• Transformed schemas (z.string().transform() or z.object().transform())
• Object or record schemas, even if they're empty
• Any other schema type