diff --git a/src/google/adk/tools/_gemini_schema_util.py b/src/google/adk/tools/_gemini_schema_util.py
index 08e8d4e6c1..6ec4f889b5 100644
--- a/src/google/adk/tools/_gemini_schema_util.py
+++ b/src/google/adk/tools/_gemini_schema_util.py
@@ -106,7 +106,11 @@ def _sanitize_schema_type(
 def _dereference_schema(schema: dict[str, Any]) -> dict[str, Any]:
   """Resolves $ref pointers in a JSON schema."""
 
-  defs = schema.get("$defs", {})
+  defs = {}
+  if isinstance(schema.get("definitions"), dict):
+    defs.update(schema["definitions"])
+  if isinstance(schema.get("$defs"), dict):
+    defs.update(schema["$defs"])
 
   def _resolve_refs(sub_schema: Any, path_refs: frozenset[str]) -> Any:
     if isinstance(sub_schema, dict):
@@ -151,6 +155,8 @@ def _resolve_refs(sub_schema: Any, path_refs: frozenset[str]) -> Any:
   # Remove the definitions block after resolving.
   if "$defs" in dereferenced_schema:
     del dereferenced_schema["$defs"]
+  if "definitions" in dereferenced_schema:
+    del dereferenced_schema["definitions"]
   return dereferenced_schema
 
 
diff --git a/tests/unittests/tools/test_gemini_schema_util.py b/tests/unittests/tools/test_gemini_schema_util.py
index d919172527..92c6e3c8f9 100644
--- a/tests/unittests/tools/test_gemini_schema_util.py
+++ b/tests/unittests/tools/test_gemini_schema_util.py
@@ -337,6 +337,55 @@ def test_to_gemini_schema_nested_dict_with_defs_and_ref(self):
     ]
     assert gemini_schema.properties["payload"].required == ["adDomain"]
 
+  def test_to_gemini_schema_nested_dict_with_draft07_definitions_and_ref(self):
+    openapi_schema = {
+        "$schema": "http://json-schema.org/draft-07/schema#",
+        "definitions": {
+            "DeviceEnum": {
+                "enum": ["GLOBAL", "desktop", "mobile"],
+                "type": "string",
+            },
+            "DomainPayload": {
+                "properties": {
+                    "adDomain": {
+                        "items": {"type": "string"},
+                        "type": "array",
+                    },
+                    "device": {
+                        "$ref": "#/definitions/DeviceEnum",
+                        "default": "GLOBAL",
+                    },
+                },
+                "required": ["adDomain"],
+                "type": "object",
+            },
+        },
+        "properties": {"payload": {"$ref": "#/definitions/DomainPayload"}},
+        "required": ["payload"],
+        "type": "object",
+    }
+    gemini_schema = _to_gemini_schema(openapi_schema)
+    assert gemini_schema.type == Type.OBJECT
+    assert gemini_schema.properties["payload"].type == Type.OBJECT
+    assert (
+        gemini_schema.properties["payload"].properties["adDomain"].type
+        == Type.ARRAY
+    )
+    assert (
+        gemini_schema.properties["payload"].properties["adDomain"].items.type
+        == Type.STRING
+    )
+    assert (
+        gemini_schema.properties["payload"].properties["device"].type
+        == Type.STRING
+    )
+    assert gemini_schema.properties["payload"].properties["device"].enum == [
+        "GLOBAL",
+        "desktop",
+        "mobile",
+    ]
+    assert gemini_schema.properties["payload"].required == ["adDomain"]
+
   def test_sanitize_integer_formats(self):
     """Test that int32 and int64 formats are preserved for integer types"""
     openapi_schema = {