Added response cost in the Usage

src/agents/extensions/models/litellm_model.py

@@ -107,6 +107,7 @@ async def get_response(
                         input_tokens=response_usage.prompt_tokens,
                         output_tokens=response_usage.completion_tokens,
                         total_tokens=response_usage.total_tokens,
+                        response_cost=response._hidden_params.get("response_cost", 0.0)
                     )
                     if response.usage
                     else Usage()

src/agents/usage.py

@@ -15,8 +15,12 @@ class Usage:
     total_tokens: int = 0
     """Total tokens sent and received, across all requests."""
 
+    response_cost: float = 0.0
+    """Total cost incurred, across all requests."""
+
     def add(self, other: "Usage") -> None:
         self.requests += other.requests if other.requests else 0
         self.input_tokens += other.input_tokens if other.input_tokens else 0
         self.output_tokens += other.output_tokens if other.output_tokens else 0
         self.total_tokens += other.total_tokens if other.total_tokens else 0
+        self.response_cost += other.response_cost if other.response_cost else 0