diff --git a/src/memory_agent/utils.py b/src/memory_agent/utils.py
index 5fd28e2..a8164b6 100644
--- a/src/memory_agent/utils.py
+++ b/src/memory_agent/utils.py
@@ -1,11 +1,25 @@
-"""Utility functions used in our graph."""
-
-
 def split_model_and_provider(fully_specified_name: str) -> dict:
-    """Initialize the configured chat model."""
+    """Split a fully specified model name into provider and model components.
+    
+    Args:
+        fully_specified_name: String in format "provider/model" (e.g., "anthropic/claude-3").
+                            If no provider is specified, returns provider=None.
+    
+    Returns:
+        Dictionary with keys "model" (str) and "provider" (str | None).
+    """
+    if not isinstance(fully_specified_name, str):
+        raise ValueError("Input must be a string")
+    
+    if not fully_specified_name:
+        raise ValueError("Input string cannot be empty")
+    
     if "/" in fully_specified_name:
         provider, model = fully_specified_name.split("/", maxsplit=1)
+        if not provider or not model:
+            raise ValueError("Provider and model must both be specified when using '/'")
     else:
         provider = None
         model = fully_specified_name
+    
     return {"model": model, "provider": provider}