diff --git a/litellm/types/llms/openai.py b/litellm/types/llms/openai.py
index 944a20049da..15be19b9802 100644
--- a/litellm/types/llms/openai.py
+++ b/litellm/types/llms/openai.py
@@ -1179,6 +1179,24 @@ class ResponseAPIUsage(BaseLiteLLMOpenAIResponseObject):
     model_config = {"extra": "allow"}
 
 
+# Optional typing for reasoning fields; API may add new values. Prefer Dict[str, Any]
+# for response parsing so new effort/summary values and new fields are accepted.
+ResponsesAPIReasoningEffort = str  # known: "none", "minimal", "low", "medium", "high", "xhigh"
+
+
+class ResponsesAPIReasoning(BaseLiteLLMOpenAIResponseObject):
+    """
+    Reasoning info on a Responses API response. All fields are optional str to accept
+    current API values and any new values OpenAI adds. Extra fields are allowed.
+    """
+
+    model_config = ConfigDict(extra="allow")
+
+    effort: Optional[str] = None
+    generate_summary: Optional[str] = None
+    summary: Optional[str] = None
+
+
 ResponsesAPIStatus = Literal[
     "completed", "failed", "in_progress", "cancelled", "queued", "incomplete"
 ]
@@ -1217,7 +1235,7 @@ class ResponsesAPIResponse(BaseLiteLLMOpenAIResponseObject):
     top_p: Optional[float] = None
     max_output_tokens: Optional[int] = None
     previous_response_id: Optional[str] = None
-    reasoning: Optional[Reasoning] = None
+    reasoning: Optional[Dict[str, Any]] = None
     status: Optional[str] = None
     text: Optional[Union["ResponseText", Dict[str, Any]]] = None
     truncation: Optional[Literal["auto", "disabled"]] = None
@@ -1227,6 +1245,18 @@ class ResponsesAPIResponse(BaseLiteLLMOpenAIResponseObject):
     # Define private attributes using PrivateAttr
     _hidden_params: dict = PrivateAttr(default_factory=dict)
 
+    @field_validator("reasoning", mode="before")
+    @classmethod
+    def validate_reasoning_to_dict(cls, value: Any) -> Optional[Dict[str, Any]]:
+        """Accept API reasoning dict (including effort 'none'/'xhigh'); always store as dict."""
+        if value is None:
+            return None
+        if isinstance(value, dict):
+            return value
+        if hasattr(value, "model_dump"):
+            return value.model_dump()
+        return value
+
     @field_validator("usage", mode="before")
     @classmethod
     def validate_usage(cls, value):
@@ -1626,12 +1656,12 @@ class ImageGenerationPartialImageEvent(BaseLiteLLMOpenAIResponseObject):
 
 
 class ErrorEventError(BaseLiteLLMOpenAIResponseObject):
-    """Nested error object within ErrorEvent"""
+    """Nested error object within ErrorEvent."""
 
     type: str  # e.g., 'invalid_request_error'
     code: str  # e.g., 'context_length_exceeded'
     message: str
-    param: Optional[str]
+    param: Optional[str] = None
 
 
 class ErrorEvent(BaseLiteLLMOpenAIResponseObject):