diff --git a/litellm/types/llms/anthropic.py b/litellm/types/llms/anthropic.py
index 1f20d4b0c7..903d429790 100644
--- a/litellm/types/llms/anthropic.py
+++ b/litellm/types/llms/anthropic.py
@@ -17,11 +17,17 @@ class AnthropicMessagesToolChoice(TypedDict, total=False):
     disable_parallel_tool_use: bool  # default is false
 
 
-class AnthropicInputSchema(TypedDict, total=False):
-    type: Optional[str]
-    properties: Optional[dict]
-    additionalProperties: Optional[bool]
-    required: Optional[List[str]]
+AnthropicInputSchema = TypedDict(
+    "AnthropicInputSchema",
+    {
+        "type": Optional[str],
+        "properties": Optional[dict],
+        "additionalProperties": Optional[bool],
+        "required": Optional[List[str]],
+        "$defs": Optional[Dict],
+    },
+    total=False,
+)
 
 
 class AnthropicMessagesTool(TypedDict, total=False):
diff --git a/tests/llm_translation/test_anthropic_completion.py b/tests/llm_translation/test_anthropic_completion.py
index 42a3cbfca3..27841140e5 100644
--- a/tests/llm_translation/test_anthropic_completion.py
+++ b/tests/llm_translation/test_anthropic_completion.py
@@ -768,6 +768,52 @@ def test_anthropic_map_openai_params_tools_and_json_schema():
     assert "Question" in json.dumps(mapped_params)
 
 
+def test_anthropic_map_openai_params_tools_with_defs():
+    args = {
+        "non_default_params": {
+            "tools": [
+                {
+                    "type": "function",
+                    "function": {
+                        "name": "create_user",
+                        "description": "Create a user from provided profile data.",
+                        "parameters": {
+                            "type": "object",
+                            "properties": {
+                                "user": {"$ref": "#/$defs/User"},
+                            },
+                            "required": ["user"],
+                            "$defs": {
+                                "User": {
+                                    "type": "object",
+                                    "properties": {
+                                        "name": {"type": "string"},
+                                        "email": {"type": "string"},
+                                    },
+                                    "required": ["name", "email"],
+                                }
+                            },
+                        },
+                    },
+                }
+            ]
+        }
+    }
+
+    mapped_params = litellm.AnthropicConfig().map_openai_params(
+        non_default_params=args["non_default_params"],
+        optional_params={},
+        model="claude-3-5-sonnet-20240620",
+        drop_params=False,
+    )
+
+    tool = mapped_params["tools"][0]
+    assert tool["input_schema"]["properties"]["user"]["$ref"] == "#/$defs/User"
+    assert (
+        tool["input_schema"]["$defs"]["User"]["properties"]["name"]["type"] == "string"
+    )
+
+
 from litellm.constants import RESPONSE_FORMAT_TOOL_NAME