ai-agents-model-parameters-when-using-openai-gpt-5-series-models-e-g-gpt-5-mi-dbd4cdef

THEN Replace the 'max_tokens' parameter with 'max_completion_tokens' in your API request to LiteLLM. Additionally, ensure 'temperature' is either omitted or set to exactly 1 (the only supported value for this model). Do not include a 'reasoning' parameter as it is also unsupported for GPT-5 models. After making these changes, redeploy your LiteLLM proxy or router instance.

response = litellm.completion(
    model="openai/gpt-5",
    messages=prompt,
    max_completion_tokens=2000,  # instead of max_tokens
    temperature=1  # or omit entirely
)