diff --git a/homeassistant/components/anthropic/config_flow.py b/homeassistant/components/anthropic/config_flow.py
index 7fc8e70c962a..7baecd07347f 100644
--- a/homeassistant/components/anthropic/config_flow.py
+++ b/homeassistant/components/anthropic/config_flow.py
@@ -577,7 +577,7 @@ class ConversationSubentryFlowHandler(ConfigSubentryFlow):
                     "format": {
                         "type": "json_schema",
                         "schema": {
-                            **to_openapi(location_schema),
+                            **to_openapi(location_schema, openapi_version="3.1.0"),
                             "additionalProperties": False,
                         },
                     }
diff --git a/homeassistant/components/anthropic/entity.py b/homeassistant/components/anthropic/entity.py
index e62a2122bb4e..7f079e17c989 100644
--- a/homeassistant/components/anthropic/entity.py
+++ b/homeassistant/components/anthropic/entity.py
@@ -150,7 +150,9 @@ def _format_tool(
 ) -> ToolParam:
     """Format tool specification."""
     unsupported_keys = {"oneOf", "anyOf", "allOf"}
-    schema = to_openapi(tool.parameters, custom_serializer=custom_serializer)
+    schema = to_openapi(
+        tool.parameters, custom_serializer=custom_serializer, openapi_version="3.1.0"
+    )
     schema = {k: v for k, v in schema.items() if k not in unsupported_keys}
 
     return ToolParam(
@@ -1114,6 +1116,7 @@ class AnthropicBaseLLMEntity(CoordinatorEntity[AnthropicCoordinator]):
                             custom_serializer=chat_log.llm_api.custom_serializer
                             if chat_log.llm_api
                             else llm.selector_serializer,
+                            openapi_version="3.1.0",
                         ),
                         "additionalProperties": False,
                     },
@@ -1162,6 +1165,7 @@ class AnthropicBaseLLMEntity(CoordinatorEntity[AnthropicCoordinator]):
                             custom_serializer=chat_log.llm_api.custom_serializer
                             if chat_log.llm_api
                             else llm.selector_serializer,
+                            openapi_version="3.1.0",
                         ),
                     )
                 )