Module
Module 2 of 6Lesson 2 of 2~17 min

Choose the mechanism that guarantees the structure

Lesson 2 of the module "From free text to a contract" in the course "Get reliable, product-ready AI outputs (JSON, schemas, function calling)".

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Lesson objective

By the end of this lesson, you will be able to tell instructions alone, JSON mode, structured outputs and function calling apart by what they guarantee, and choose the mechanism that fits a product need.

Where it fits

From free text to a contract

Which outputs of my product must become a contract, and which mechanism should I use to get it?

Lessons in this module

  1. Diagnose where free text breaks your product
  2. Choose the mechanism that guarantees the structure (this lesson)

What you will learn in the course

This lesson is part of the course Get reliable, product-ready AI outputs (JSON, schemas, function calling)

  • Diagnose where free-text output breaks a feature and decide which outputs require a contract.
  • Choose between instructions alone, JSON mode, structured outputs and function calling for a given need, and justify the choice.
  • Design an output schema (types, enums, required fields, nullable fields, descriptions, "unknown" values) where every field serves a consumer.
  • Specify validation (syntax, schema, business rules), retries, handling of refusals and truncation, and the fallback path.
  • Version and evolve an output contract without breaking its consumers, accounting for provider differences and the split of roles between PM and developers.
  • Build a set of 20 robustness cases and set acceptance thresholds before going to production.

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