diff --git a/src/opengradient/client/llm.py b/src/opengradient/client/llm.py
index ed54fd9..622fed5 100644
--- a/src/opengradient/client/llm.py
+++ b/src/opengradient/client/llm.py
@@ -47,6 +47,17 @@ class _ChatParams:
     x402_settlement_mode: x402SettlementMode
 
 
+def _get_model_id(model) -> str:
+    """Extract model ID from provider/model-name format, raising ValueError for invalid formats."""
+    value = model.value if hasattr(model, "value") else str(model)
+    parts = value.split("/", 1)
+    if len(parts) != 2:
+        raise ValueError(
+            f"Invalid model identifier '{value}'. Expected 'provider/model-name' format."
+        )
+    return parts[1]
+
+
 class LLM:
     """
     LLM inference namespace.
@@ -252,7 +263,7 @@ async def completion(
         Raises:
             RuntimeError: If the inference fails.
         """
-        model_id = model.split("/")[1]
+        model_id = _get_model_id(model)
         payload: Dict = {
             "model": model_id,
             "prompt": prompt,
@@ -327,7 +338,7 @@ async def chat(
             RuntimeError: If the inference fails.
         """
         params = _ChatParams(
-            model=model.split("/")[1],
+            model=_get_model_id(model),
             max_tokens=max_tokens,
             temperature=temperature,
             stop_sequence=stop_sequence,