Temperature parameter included in GPT-5 prompts from SDK

Last updated: February 20, 2026

This issue is applicable to customers matching these conditions

Plans: Any

Deployments: Any

Use case: SDK prompt fetching with GPT-5 models when passing parameters directly to OpenAI API

Summary

Issue: When using the Braintrust SDK to fetch prompts configured for GPT-5 models, the returned prompt parameters include temperature: 0 even though GPT-5 models don't support the temperature parameter. This causes errors when passing these parameters directly to OpenAI's API.

Cause: Braintrust prompt storage includes temperature parameters for all models, but GPT-5 models reject any temperature setting in API calls.

Resolution: Filter out the temperature parameter from prompt parameters before sending to OpenAI, or use Braintrust's AI proxy which handles this automatically.

Resolution Steps

Remove temperature from fetched parameters

Filter out the temperature parameter when using GPT-5 models before calling OpenAI.