diff --git a/litellm/litellm_core_utils/token_counter.py b/litellm/litellm_core_utils/token_counter.py
index 5e6df8d9d95..819bdaf7645 100644
--- a/litellm/litellm_core_utils/token_counter.py
+++ b/litellm/litellm_core_utils/token_counter.py
@@ -769,15 +769,20 @@ def _format_function_definitions(tools):
         function = tool.get("function")
         if function is None:
             # Anthropic tool shape → OpenAI function dict for token counting.
+            params = tool.get("input_schema") or tool.get("parameters") or {}
+            if not isinstance(params, dict):
+                params = {}
             function = {
                 "name": tool.get("name"),
                 "description": tool.get("description"),
-                "parameters": tool.get("input_schema", tool.get("parameters", {})),
+                "parameters": params,
             }
         if function_description := function.get("description"):
             lines.append(f"// {function_description}")
         function_name = function.get("name")
-        parameters = function.get("parameters", {})
+        parameters = function.get("parameters") or {}
+        if not isinstance(parameters, dict):
+            parameters = {}
         properties = parameters.get("properties")
         if properties and properties.keys():
             lines.append(f"type {function_name} = (_: {{")