diff --git a/src/platform/configuration/common/configurationService.ts b/src/platform/configuration/common/configurationService.ts
index 59af216cee..97c924930d 100644
--- a/src/platform/configuration/common/configurationService.ts
+++ b/src/platform/configuration/common/configurationService.ts
@@ -813,7 +813,7 @@ export namespace ConfigKey {
 	/** Configure reasoning effort sent to Responses API */
 	export const ResponsesApiReasoningEffort = defineSetting<'low' | 'medium' | 'high' | 'default'>('chat.responsesApiReasoningEffort', ConfigType.ExperimentBased, 'default');
 	/** Configure reasoning summary style sent to Responses API */
-	export const ResponsesApiReasoningSummary = defineSetting<'off' | 'detailed'>('chat.responsesApiReasoningSummary', ConfigType.ExperimentBased, 'detailed');
+	export const ResponsesApiReasoningSummary = defineSetting<'off' | 'concise' | 'detailed'>('chat.responsesApiReasoningSummary', ConfigType.ExperimentBased, 'detailed');
 	export const EnableChatImageUpload = defineSetting<boolean>('chat.imageUpload.enabled', ConfigType.ExperimentBased, true);
 	/** Thinking token budget for Anthropic extended thinking. If set, enables extended thinking. */
 	export const AnthropicThinkingBudget = defineSetting<number>('chat.anthropic.thinking.budgetTokens', ConfigType.ExperimentBased, 4000);
diff --git a/src/platform/endpoint/common/chatModelCapabilities.ts b/src/platform/endpoint/common/chatModelCapabilities.ts
index c2923d8ca0..bc545e6f9e 100644
--- a/src/platform/endpoint/common/chatModelCapabilities.ts
+++ b/src/platform/endpoint/common/chatModelCapabilities.ts
@@ -29,7 +29,8 @@ const VSC_MODEL_HASHES_A = [
 const HIDDEN_MODEL_B_HASHES = [
 	'31a2d5282683edb3a22c565f199aa96fb9ffb3107af35aad92ee1cd567cfc25d',
 	'dd832404e8eeb90793f0369b96ed1702e0e22487a58eb4c1f285a4af5c4f6f21',
-	'131e2083b68bde4fe879efc38ed9651b1623f8735eeb42157fa3b63ef943fdc6'
+	'131e2083b68bde4fe879efc38ed9651b1623f8735eeb42157fa3b63ef943fdc6',
+	'768e03eb8c0003f009745eb72538a435874c5b52a3e4cc71714ca06ceca60d29',
 ];
 
 // Currently empty, will be used in future for a different set of VSC models
diff --git a/src/platform/endpoint/node/responsesApi.ts b/src/platform/endpoint/node/responsesApi.ts
index 5dddec64aa..ef2d6b1bf2 100644
--- a/src/platform/endpoint/node/responsesApi.ts
+++ b/src/platform/endpoint/node/responsesApi.ts
@@ -23,7 +23,7 @@ import { ChatCompletion, FinishedCompletionReason, TokenLogProb } from '../../ne
 import { IExperimentationService } from '../../telemetry/common/nullExperimentationService';
 import { ITelemetryService } from '../../telemetry/common/telemetry';
 import { TelemetryData } from '../../telemetry/common/telemetryData';
-import { getVerbosityForModelSync } from '../common/chatModelCapabilities';
+import { getVerbosityForModelSync, isHiddenModelB } from '../common/chatModelCapabilities';
 import { getStatefulMarkerAndIndex } from '../common/statefulMarkerContainer';
 import { rawPartAsThinkingData } from '../common/thinkingDataContainer';
 
@@ -57,8 +57,12 @@ export function createResponsesRequestBody(accessor: ServicesAccessor, options:
 		'disabled';
 	const effortConfig = configService.getExperimentBasedConfig(ConfigKey.ResponsesApiReasoningEffort, expService);
 	const summaryConfig = configService.getExperimentBasedConfig(ConfigKey.ResponsesApiReasoningSummary, expService);
-	const effort = effortConfig === 'default' ? 'medium' : effortConfig;
-	const summary = summaryConfig === 'off' ? undefined : summaryConfig;
+	let effort = effortConfig === 'default' ? 'medium' : effortConfig;
+	let summary = summaryConfig === 'off' ? 'detailed' : summaryConfig;
+	const reasoningParams = reasoningParameterValuesBasedOnModel(endpoint.family, effort, summary);
+	effort = reasoningParams?.effort || effort;
+	summary = reasoningParams?.summary || summary;
+
 	if (effort || summary) {
 		body.reasoning = {
 			...(effort ? { effort } : {}),
@@ -71,6 +75,20 @@ export function createResponsesRequestBody(accessor: ServicesAccessor, options:
 	return body;
 }
 
+// for gpt-5.2 + models, changing the default reasoning parameters
+type ResponsesReasoningEffort = 'low' | 'medium' | 'high';
+type ResponsesReasoningSummary = 'concise' | 'detailed';
+
+function reasoningParameterValuesBasedOnModel(model: string, effort: ResponsesReasoningEffort, summary: ResponsesReasoningSummary): { effort?: ResponsesReasoningEffort; summary?: ResponsesReasoningSummary } | undefined {
+	if (isHiddenModelB(model)) {
+		return {
+			effort,
+			summary: 'concise',
+		};
+	}
+}
+
+
 function rawMessagesToResponseAPI(modelId: string, messages: readonly Raw.ChatMessage[], ignoreStatefulMarker: boolean): { input: OpenAI.Responses.ResponseInputItem[]; previous_response_id?: string } {
 	const statefulMarkerAndIndex = !ignoreStatefulMarker && getStatefulMarkerAndIndex(modelId, messages);
 	let previousResponseId: string | undefined;