diff --git a/.gitignore b/.gitignore
index 7e434174..186f9452 100644
--- a/.gitignore
+++ b/.gitignore
@@ -243,3 +243,6 @@ package.json
 tau2-bench
 *.err
 eval-protocol
+_pytest_deps/
+.test_deps/
+.test_deps/
diff --git a/eval_protocol/generic_server.py b/eval_protocol/generic_server.py
index 04e111e2..bf6945d6 100644
--- a/eval_protocol/generic_server.py
+++ b/eval_protocol/generic_server.py
@@ -1,4 +1,5 @@
 import importlib
+import logging
 import os
 from typing import Any, Dict, List, Optional
 
@@ -9,12 +10,15 @@
 # Assuming these models are correctly defined in eval_protocol.models
 from eval_protocol.models import EvaluateResult, Message
 
+logger = logging.getLogger(__name__)
+
 
 # --- Request and Response Models ---
 class EvaluationRequest(BaseModel):
     messages: List[Dict[str, Any]]  # Could also be List[Message] if we enforce that model on input
     ground_truth: Optional[str] = None
-    kwargs: Optional[Dict[str, Any]] = {}
+    # Avoid shared mutable default across requests.
+    kwargs: Optional[Dict[str, Any]] = None
 
 
 # --- Global variable to store the loaded reward function ---
@@ -74,8 +78,10 @@ async def evaluate_endpoint(request: EvaluationRequest):
         if not isinstance(result, EvaluateResult):
             # This case should ideally not happen if functions are correctly decorated
             # and return EvaluateResult, but good to have a fallback.
-            print(
-                f"Warning: Reward function '{_REWARD_FUNCTION_NAME}' did not return an EvaluateResult instance. Type: {type(result)}"
+            logger.warning(
+                "Reward function '%s' did not return an EvaluateResult instance. Type: %s",
+                _REWARD_FUNCTION_NAME,
+                type(result),
             )
             # Attempt to construct an EvaluateResult if it's a dict-like object,
             # otherwise, this will raise an error or return a poorly formed response.
@@ -89,15 +95,18 @@ async def evaluate_endpoint(request: EvaluationRequest):
 
         return result
     except ValidationError as ve:  # Pydantic validation error from reward function's input/output
-        print(f"Validation Error calling reward function '{_REWARD_FUNCTION_NAME}': {ve}")
+        logger.warning(
+            "Validation error calling reward function '%s': %s",
+            _REWARD_FUNCTION_NAME,
+            ve,
+        )
         raise HTTPException(
             status_code=422,
             detail=f"Input/Output validation error for reward function: {ve.errors()}",
         )
     except Exception as e:
-        print(f"Error during evaluation with reward function '{_REWARD_FUNCTION_NAME}': {e}")
-        # Consider logging the full traceback here
-        raise HTTPException(status_code=500, detail=f"Internal server error during evaluation: {str(e)}")
+        logger.exception("Error during evaluation with reward function '%s'", _REWARD_FUNCTION_NAME)
+        raise HTTPException(status_code=500, detail="Internal server error during evaluation.")
 
 
 @app.get("/health")
@@ -121,9 +130,9 @@ def load_reward_function(import_string: str):
         module = importlib.import_module(module_path)
         _LOADED_REWARD_FUNCTION = getattr(module, function_name)
         _REWARD_FUNCTION_NAME = import_string
-        print(f"Successfully loaded reward function: {_REWARD_FUNCTION_NAME}")
+        logger.info("Successfully loaded reward function: %s", _REWARD_FUNCTION_NAME)
     except Exception as e:
-        print(f"Error loading reward function from '{import_string}': {e}")
+        logger.exception("Error loading reward function from '%s'", import_string)
         _LOADED_REWARD_FUNCTION = None
         _REWARD_FUNCTION_NAME = "Error loading"
         raise  # Re-raise to make it fatal if loading fails on startup
@@ -153,13 +162,16 @@ def load_reward_function(import_string: str):
     try:
         load_reward_function(args.import_string)
     except Exception:
-        print("Failed to load reward function. Exiting.")
+        logger.error("Failed to load reward function. Exiting.")
         exit(1)
 
     if not _LOADED_REWARD_FUNCTION:
-        print(f"Reward function {_REWARD_FUNCTION_NAME} could not be loaded. Server will not start correctly.")
+        logger.error(
+            "Reward function %s could not be loaded. Server will not start correctly.",
+            _REWARD_FUNCTION_NAME,
+        )
         # Depending on desired behavior, could exit here or let it run and fail on /evaluate
         exit(1)
 
-    print(f"Starting server for reward function: {args.import_string} on http://{args.host}:{args.port}")
+    logger.info("Starting server for reward function: %s on http://%s:%s", args.import_string, args.host, args.port)
     uvicorn.run(app, host=args.host, port=args.port)  # reload=args.reload for dev
diff --git a/tests/test_generic_server.py b/tests/test_generic_server.py
index 94beb0aa..635bb3d0 100644
--- a/tests/test_generic_server.py
+++ b/tests/test_generic_server.py
@@ -168,7 +168,11 @@ def test_evaluate_endpoint_reward_function_raises_error(self):
         request_payload = EvaluationRequest(messages=[{"role": "user", "content": "test"}])
         response = self.client.post("/evaluate", json=request_payload.model_dump())
         assert response.status_code == 500
-        assert "Intentional error in dummy_reward_func_error" in response.json()["detail"]
+        assert response.json()["detail"] == "Internal server error during evaluation."
+
+    def test_evaluation_request_kwargs_defaults_to_none(self):
+        payload = EvaluationRequest(messages=[{"role": "user", "content": "test"}])
+        assert payload.kwargs is None
 
     def test_evaluate_endpoint_function_returns_invalid_type(self):
         """