Updated input parameter support for OpenAI 5.1 models when reasoning effort = "None"

[choffer1120]

Description

Logprobs, temperature and top-p are controllable parameters on gpt-5.1 when reasoning effort is set to "none". See OpenAI docs here

However, the AI SDK has a blanket rule disabling of these parameters for all reasoning models purely on model name/id:

ai/packages/openai/src/chat/openai-chat-language-model.ts

Lines 168 to 223 in 7b8aca6

	if (isReasoningModel(this.modelId)) {
	// remove unsupported settings for reasoning models
	// see https://platform.openai.com/docs/guides/reasoning#limitations
	if (baseArgs.temperature != null) {
	baseArgs.temperature = undefined;
	warnings.push({
	type: 'unsupported',
	feature: 'temperature',
	details: 'temperature is not supported for reasoning models',
	});
	}
	if (baseArgs.top_p != null) {
	baseArgs.top_p = undefined;
	warnings.push({
	type: 'unsupported',
	feature: 'topP',
	details: 'topP is not supported for reasoning models',
	});
	}
	if (baseArgs.frequency_penalty != null) {
	baseArgs.frequency_penalty = undefined;
	warnings.push({
	type: 'unsupported',
	feature: 'frequencyPenalty',
	details: 'frequencyPenalty is not supported for reasoning models',
	});
	}
	if (baseArgs.presence_penalty != null) {
	baseArgs.presence_penalty = undefined;
	warnings.push({
	type: 'unsupported',
	feature: 'presencePenalty',
	details: 'presencePenalty is not supported for reasoning models',
	});
	}
	if (baseArgs.logit_bias != null) {
	baseArgs.logit_bias = undefined;
	warnings.push({
	type: 'other',
	message: 'logitBias is not supported for reasoning models',
	});
	}
	if (baseArgs.logprobs != null) {
	baseArgs.logprobs = undefined;
	warnings.push({
	type: 'other',
	message: 'logprobs is not supported for reasoning models',
	});
	}
	if (baseArgs.top_logprobs != null) {
	baseArgs.top_logprobs = undefined;
	warnings.push({
	type: 'other',
	message: 'topLogprobs is not supported for reasoning models',
	});
	}

Assuming one would need to pass reasoning effort (if supplied) alongside the modelId to determine if isReasoningModel is true. But would be amazing if these could be opened up on AI SDK, we are heavy logprob users and will have to move back off the AI SDK in order to use 5.1 with no reasoning.

Thanks so much, and happy to take a crack at it if that would be easier 🫡

AI SDK Version

ai: "^5.0"
@ai-sdk/openai: "^2.0"

Code of Conduct

• I agree to follow this project's Code of Conduct

[lgrammel]

Identify issue type

Identified as Bug
Confidence: High

Rationale

This is a concrete provider compatibility failure: the SDK incorrectly suppresses parameters that GPT-5.1 supports under a specific reasoning-effort setting.

Evidence

• The OpenAI provider disables logprobs, temperature, and top-p based solely on the model ID being classified as a reasoning model.
• GPT-5.1 supports those parameters when reasoning effort is set to "none", but the SDK does not account for that setting.
• The reporter cannot use supported GPT-5.1 parameters through the current AI SDK behavior.