What changed in GPT-5.4 and how to update your OpenDunes integration when moving from earlier GPT-5 versions.
GPT-5.4 is a capability update in OpenAI's GPT-5 generation. It is available on OpenDunes under the slug openai/gpt-5.4 and is a drop-in replacement for openai/gpt-5.2 and earlier GPT-5 revisions. This guide covers what changed and how to migrate.
GPT-5.4 handles documents near the top of the context window more accurately. Tasks that involve retrieving specific facts from long transcripts, contracts, or reports — and that previously required careful chunking — now work more reliably with the full document in context.
Arabic, French, and Darija (Algerian Arabic) output quality improved. Applications serving Algerian end-users who write in mixed Arabic/French will see more natural responses. No prompt changes are required; the improvement is model-side.
GPT-5.4 supports tool/function calling through POST /v1/chat/completions today — pass tools and tool_choice as usual. It uses the same tool schema format as the prior GPT-5 revisions, so no structural changes are needed.
GPT-5.4 is more concise by default. Responses that previously required "be brief, no more than three sentences" instructions may now behave correctly without them. Test your prompts — if you had verbosity-suppression language, it may be safe to remove.
GPT-5.4 supports response_format: { type: "json_object" } today, with improved schema adherence versus GPT-5.2.
No breaking changes to parameter semantics. Note:
temperature: the model's baseline is slightly more conservative at the same temperature value versus GPT-5.2. If outputs feel less varied than expected, nudge temperature up by 0.1–0.2.max_tokens: GPT-5.4 outputs tend to be shorter (fewer filler words). Your existing max_tokens ceiling is unlikely to be a bottleneck, but recalibrate if you were tuning it tightly against average output length.GPT-5.4 is priced per million input and output tokens in DA, at a higher rate than GPT-5.2; check the model catalog for the current figures before estimating production costs.
Change the model string back to openai/gpt-5.2. All model versions remain in the catalog simultaneously — OpenDunes does not deprecate slugs without advance notice.