diff --git a/.changeset/brave-swans-smile.md b/.changeset/brave-swans-smile.md
new file mode 100644
index 00000000..d4aa0e1d
--- /dev/null
+++ b/.changeset/brave-swans-smile.md
@@ -0,0 +1,5 @@
+---
+'@openai/agents-openai': patch
+---
+
+Pass through strict flag for function tools when using completion
diff --git a/packages/agents-openai/src/openaiChatCompletionsConverter.ts b/packages/agents-openai/src/openaiChatCompletionsConverter.ts
index bfa44525..606dfd26 100644
--- a/packages/agents-openai/src/openaiChatCompletionsConverter.ts
+++ b/packages/agents-openai/src/openaiChatCompletionsConverter.ts
@@ -277,6 +277,7 @@ export function toolToOpenAI(tool: SerializedTool): ChatCompletionTool {
         name: tool.name,
         description: tool.description || '',
         parameters: tool.parameters,
+        strict: tool.strict,
       },
     };
   }
diff --git a/packages/agents-openai/test/openaiChatCompletionsConverter.test.ts b/packages/agents-openai/test/openaiChatCompletionsConverter.test.ts
index b85c2867..88881a72 100644
--- a/packages/agents-openai/test/openaiChatCompletionsConverter.test.ts
+++ b/packages/agents-openai/test/openaiChatCompletionsConverter.test.ts
@@ -253,6 +253,7 @@ describe('tool helpers', () => {
           required: [],
           additionalProperties: false,
         },
+        strict: true,
       },
     });
   });