diff --git a/evaluation_function/evaluation.py b/evaluation_function/evaluation.py
index 7ed9066..708465f 100755
--- a/evaluation_function/evaluation.py
+++ b/evaluation_function/evaluation.py
@@ -5,49 +5,58 @@
 from .correction import analyze_fsa_correction
 
 def validate_fsa(value: str | dict) -> FSA:
+    """Parse a FSA from JSON string or dict."""
     if isinstance(value, str):
         return FSA.model_validate_json(value)
     return FSA.model_validate(value)
 
-def evaluation_function(payload: Any) -> LFResult:
+def evaluation_function(
+    response: Any = None,
+    answer: Any = None,
+    params: Any = None  # Temp workaround: treat params as Any
+) -> LFResult:
     """
-    Evaluate a student's FSA response against the expected answer.
+    Temporary FSA evaluation function.
     
     Args:
-        payload: dict with keys 'response', 'answer', 'params' (front-end may wrap everything)
+        response: Student's FSA (may be None if frontend wraps everything in params)
+        answer: Expected FSA (may be None)
+        params: Additional parameters (or full payload if frontend wraps everything here)
     
     Returns:
-        LFResult
+        LFResult with is_correct and feedback_items
     """
     try:
-        # Extract response/answer from the payload
-        raw_response = payload.get("response") or payload.get("params", {}).get("response")
-        raw_answer = payload.get("answer") or payload.get("params", {}).get("answer")
-        params = payload.get("params", {})
+        # Extract student and expected FSAs from whatever is present
+        raw_response = response or getattr(params, "response", None) or params.get("response", None)
+        raw_answer = answer or getattr(params, "answer", None) or params.get("answer", None)
+        extra_params = params.get("params") or params
 
         if raw_response is None or raw_answer is None:
-            raise ValueError("Missing response or answer in payload")
+            raise ValueError("Missing FSA data: response or answer is None")
 
         # Parse FSAs
         student_fsa = validate_fsa(raw_response)
         expected_fsa = validate_fsa(raw_answer)
 
-        require_minimal = params.get("require_minimal", False)
+        require_minimal = extra_params.get("require_minimal", False) if isinstance(extra_params, dict) else False
 
-        # Run correction
+        # Run correction pipeline
         result: Result = analyze_fsa_correction(student_fsa, expected_fsa, require_minimal)
 
-        # Convert to LFResult
+        # Return LFResult
         return LFResult(
             is_correct=result.is_correct,
             feedback_items=[("feedback", result.feedback)]
         )
 
     except Exception as e:
+        # Always return LFResult with raw payload for debugging
         return LFResult(
             is_correct=False,
             feedback_items=[(
                 "error",
-                f"Invalid FSA format: {str(e)}\n\npayload received:\n{payload}"
+                f"Invalid FSA format: {str(e)}\n\n"
+                f"response: {response}\nanswer: {answer}\nparams: {params}"
             )]
         )