# OpenAI — Building with the GPT-5 Model Series: A Practical Guide

- Company: OpenAI (openai.com)
- Announced: 2026-01-15T00:09:56+00:00
- Category: not stated
- Coverage: not counted
- Announcement: no
- Group: routine
- Source: https://openai.com/business/guides-and-resources/a-practical-guide-to-building-with-ai
- Record: https://forck.live/items/18797-building-with-the-gpt-5-model-series-a-practical-guide
- Subject: GPT / ChatGPT / API
- Models affected: GPT-5, GPT-4.1

OpenAI published a practical guide for startups on building with GPT-5, covering migration to the Responses API, prompt optimization, and new steering controls such as reasoning_effort and verbosity. The guide states GPT-5 scored 74.9% on SWE-bench Verified and is described as faster, smarter, and more steerable than previous models.

## Evidence

Verbatim from https://openai.com/business/guides-and-resources/a-practical-guide-to-building-with-ai:

> GPT‑5 introduces new controls that let you fine-tune how the model reasons and communicates. These capabilities help startups match model effort and output to the unique complexity of their products.

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