diff --git a/nanobot/providers/litellm_provider.py b/nanobot/providers/litellm_provider.py
index 7865139..a39893b 100644
--- a/nanobot/providers/litellm_provider.py
+++ b/nanobot/providers/litellm_provider.py
@@ -122,6 +122,10 @@ class LiteLLMProvider(LLMProvider):
         """
         model = self._resolve_model(model or self.default_model)
         
+        # Clamp max_tokens to at least 1 — negative or zero values cause
+        # LiteLLM to reject the request with "max_tokens must be at least 1".
+        max_tokens = max(1, max_tokens)
+        
         kwargs: dict[str, Any] = {
             "model": model,
             "messages": messages,