diff --git a/src/api/providers/__tests__/openai.spec.ts b/src/api/providers/__tests__/openai.spec.ts
index 73b542dbc73..5299c297e8e 100644
--- a/src/api/providers/__tests__/openai.spec.ts
+++ b/src/api/providers/__tests__/openai.spec.ts
@@ -635,7 +635,6 @@ describe("OpenAiHandler", () => {
 					temperature: 0,
 					tools: undefined,
 					tool_choice: undefined,
-					parallel_tool_calls: true,
 				},
 				{ path: "/models/chat/completions" },
 			)
@@ -684,7 +683,6 @@ describe("OpenAiHandler", () => {
 					],
 					tools: undefined,
 					tool_choice: undefined,
-					parallel_tool_calls: true,
 				},
 				{ path: "/models/chat/completions" },
 			)
diff --git a/src/api/providers/base-openai-compatible-provider.ts b/src/api/providers/base-openai-compatible-provider.ts
index fc3d769ae2a..e87f1478992 100644
--- a/src/api/providers/base-openai-compatible-provider.ts
+++ b/src/api/providers/base-openai-compatible-provider.ts
@@ -95,7 +95,7 @@ export abstract class BaseOpenAiCompatibleProvider<ModelName extends string>
 			stream_options: { include_usage: true },
 			tools: this.convertToolsForOpenAI(metadata?.tools),
 			tool_choice: metadata?.tool_choice,
-			parallel_tool_calls: metadata?.parallelToolCalls ?? true,
+			...(metadata?.parallelToolCalls === true && { parallel_tool_calls: true }),
 		}
 
 		// Add thinking parameter if reasoning is enabled and model supports it
diff --git a/src/api/providers/openai.ts b/src/api/providers/openai.ts
index 87589b93960..db0606ceed2 100644
--- a/src/api/providers/openai.ts
+++ b/src/api/providers/openai.ts
@@ -161,7 +161,7 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 				...(reasoning && reasoning),
 				tools: this.convertToolsForOpenAI(metadata?.tools),
 				tool_choice: metadata?.tool_choice,
-				parallel_tool_calls: metadata?.parallelToolCalls ?? true,
+				...(metadata?.parallelToolCalls === true && { parallel_tool_calls: true }),
 			}
 
 			// Add max_tokens if needed
@@ -229,7 +229,7 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 				// Tools are always present (minimum ALWAYS_AVAILABLE_TOOLS)
 				tools: this.convertToolsForOpenAI(metadata?.tools),
 				tool_choice: metadata?.tool_choice,
-				parallel_tool_calls: metadata?.parallelToolCalls ?? true,
+				...(metadata?.parallelToolCalls === true && { parallel_tool_calls: true }),
 			}
 
 			// Add max_tokens if needed
@@ -348,7 +348,7 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 				// Tools are always present (minimum ALWAYS_AVAILABLE_TOOLS)
 				tools: this.convertToolsForOpenAI(metadata?.tools),
 				tool_choice: metadata?.tool_choice,
-				parallel_tool_calls: metadata?.parallelToolCalls ?? true,
+				...(metadata?.parallelToolCalls === true && { parallel_tool_calls: true }),
 			}
 
 			// O3 family models do not support the deprecated max_tokens parameter
@@ -382,7 +382,7 @@ export class OpenAiHandler extends BaseProvider implements SingleCompletionHandl
 				// Tools are always present (minimum ALWAYS_AVAILABLE_TOOLS)
 				tools: this.convertToolsForOpenAI(metadata?.tools),
 				tool_choice: metadata?.tool_choice,
-				parallel_tool_calls: metadata?.parallelToolCalls ?? true,
+				...(metadata?.parallelToolCalls === true && { parallel_tool_calls: true }),
 			}
 
 			// O3 family models do not support the deprecated max_tokens parameter