Resolve test failure

Author: gilbertl

packages/agents-openai/src/openaiChatCompletionsModel.ts

@@ -67,7 +67,13 @@ export class OpenAIChatCompletionsModel implements Model {
     const output: protocol.OutputModelItem[] = [];
     if (response.choices && response.choices[0]) {
       const message = response.choices[0].message;
-      if (message.content !== undefined && message.content !== null && message.content !== '') {
+      
+      if (
+        message.content !== undefined &&
+        message.content !== null &&
+        // Azure OpenAI returns empty string instead of null for tool calls, causing parser rejection
+        !(message.tool_calls && message.content === '')
+      ) {
         const { content, ...rest } = message;
         output.push({
           id: response.id,