The context · August 2025
OpenAI introduced GPT-5 for developers in August 2025, presenting a new option for coding, reasoning and tool-using applications. [1]
Your workload is the benchmark
A model can improve on published evaluations while becoming less suitable for a particular application. Response style, tool choices, latency and the handling of incomplete questions all matter. Existing users may depend on behaviours that a general benchmark never measures.
Keep the comparison fair
Run the current and candidate models on the same representative requests. Include difficult cases that already required human intervention. Review the outputs without identifying the model where practical. Look separately at successful routine work and the errors that could create the greatest disruption.
Make switching reversible
Keep the current configuration available while a small share of suitable traffic is evaluated. Define who can stop the rollout and what signal would trigger that decision. A model upgrade should have an owner, an acceptance standard and a recovery path, just like any other product change.
Source & context
OpenAI · GPT-5 for developers, 7 August 2025This retrospective was written for the archive in September 2026. The linked primary source documents the announcement or event; the practical interpretation and proposed approach are Sansa’s editorial perspective. Public examples do not imply a client relationship. Product capabilities and guidance may have changed since the period discussed.
Another perspective · August 2025
A model-upgrade gate for an existing AI feature
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