return string of dict

app.py

@@ -90,7 +90,7 @@ async def predict(request: PredictionRequest):  # ← Validates input automatica
 
 @app.post("/evaluate")
 async def evaluate(request: EvaluationRequest):  # ← Validates input automatically
-    return evaluate_batch(request.file_path, hf_repo, backend="local")
+    return str(evaluate_batch(request.file_path, hf_repo, backend="local"))
 
 @app.get("/health")
 def health_check():