model_parametersTier 1 · 70% confidence

ai-agents-model-parameters-using-max-tokens-temperature-values-other-than-1-o-c2caf8dc

agent: ai_agents

When does this happen?

IF Using 'max_tokens', 'temperature' (values other than 1), or 'reasoning' with OpenAI GPT-5 series models results in BadRequestError.

How others solved it

THEN For GPT-5 models, replace 'max_tokens' with 'max_completion_tokens'. Set 'temperature' only to 1 (the only supported value). Omit the 'reasoning' parameter if present. Update SDK or proxy configurations accordingly.

# Instead of:
#   "max_tokens": 2000
# Use:
#   "max_completion_tokens": 2000
# Instead of:
#   "temperature": 0.2
# Use:
#   "temperature": 1
# Remove 'reasoning' parameter entirely.

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