refactor: move Authorization validation from API model to handler layer

Per reviewer feedback, API models should be pure data structures without
business logic. Moved the Authorization header validation from the Pydantic
@model_validator in openai_responses.py to the handler in streaming.py.

- Removed @model_validator from OpenAIResponseInputToolMCP
- Added validation at handler level in _process_mcp_tool()
- Maintains same security check: rejects Authorization in headers dict
- Follows separation of concerns: models are data, handlers have logic

src/llama_stack/apis/agents/openai_responses.py

@@ -7,12 +7,12 @@
 from collections.abc import Sequence
 from typing import Annotated, Any, Literal
 
-from pydantic import BaseModel, Field, model_validator
-from typing_extensions import TypedDict
-
 from llama_stack.apis.vector_io import SearchRankingOptions as FileSearchRankingOptions
 from llama_stack.schema_utils import json_schema_type, register_schema
 
+from pydantic import BaseModel, Field, model_validator
+from typing_extensions import TypedDict
+
 # NOTE(ashwin): this file is literally a copy of the OpenAI responses API schema. We should probably
 # take their YAML and generate this file automatically. Their YAML is available.
 
@@ -89,7 +89,9 @@ OpenAIResponseInputMessageContent = Annotated[
     | OpenAIResponseInputMessageContentFile,
     Field(discriminator="type"),
 ]
-register_schema(OpenAIResponseInputMessageContent, name="OpenAIResponseInputMessageContent")
+register_schema(
+    OpenAIResponseInputMessageContent, name="OpenAIResponseInputMessageContent"
+)
 
 
 @json_schema_type
@@ -191,7 +193,9 @@ OpenAIResponseOutputMessageContent = Annotated[
     OpenAIResponseOutputMessageContentOutputText | OpenAIResponseContentPartRefusal,
     Field(discriminator="type"),
 ]
-register_schema(OpenAIResponseOutputMessageContent, name="OpenAIResponseOutputMessageContent")
+register_schema(
+    OpenAIResponseOutputMessageContent, name="OpenAIResponseOutputMessageContent"
+)
 
 
 @json_schema_type
@@ -203,8 +207,17 @@ class OpenAIResponseMessage(BaseModel):
     scenarios.
     """
 
-    content: str | Sequence[OpenAIResponseInputMessageContent] | Sequence[OpenAIResponseOutputMessageContent]
+    content: (
-    role: Literal["system"] | Literal["developer"] | Literal["user"] | Literal["assistant"]
+        str
+        | Sequence[OpenAIResponseInputMessageContent]
+        | Sequence[OpenAIResponseOutputMessageContent]
+    )
+    role: (
+        Literal["system"]
+        | Literal["developer"]
+        | Literal["user"]
+        | Literal["assistant"]
+    )
     type: Literal["message"] = "message"
 
     # The fields below are not used in all scenarios, but are required in others.
@@ -258,7 +271,9 @@ class OpenAIResponseOutputMessageFileSearchToolCall(BaseModel):
     queries: Sequence[str]
     status: str
     type: Literal["file_search_call"] = "file_search_call"
-    results: Sequence[OpenAIResponseOutputMessageFileSearchToolCallResults] | None = None
+    results: Sequence[OpenAIResponseOutputMessageFileSearchToolCallResults] | None = (
+        None
+    )
 
 
 @json_schema_type
@@ -403,7 +418,11 @@ class OpenAIResponseText(BaseModel):
 
 
 # Must match type Literals of OpenAIResponseInputToolWebSearch below
-WebSearchToolTypes = ["web_search", "web_search_preview", "web_search_preview_2025_03_11"]
+WebSearchToolTypes = [
+    "web_search",
+    "web_search_preview",
+    "web_search_preview_2025_03_11",
+]
 
 
 @json_schema_type
@@ -415,11 +434,15 @@ class OpenAIResponseInputToolWebSearch(BaseModel):
     """
 
     # Must match values of WebSearchToolTypes above
-    type: Literal["web_search"] | Literal["web_search_preview"] | Literal["web_search_preview_2025_03_11"] = (
+    type: (
-        "web_search"
+        Literal["web_search"]
-    )
+        | Literal["web_search_preview"]
+        | Literal["web_search_preview_2025_03_11"]
+    ) = "web_search"
     # TODO: actually use search_context_size somewhere...
-    search_context_size: str | None = Field(default="medium", pattern="^low|medium|high$")
+    search_context_size: str | None = Field(
+        default="medium", pattern="^low|medium|high$"
+    )
     # TODO: add user_location
 
 
@@ -502,22 +525,6 @@ class OpenAIResponseInputToolMCP(BaseModel):
     require_approval: Literal["always"] | Literal["never"] | ApprovalFilter = "never"
     allowed_tools: list[str] | AllowedToolsFilter | None = None
 
-    @model_validator(mode="after")
-    def validate_no_auth_in_headers(self) -> "OpenAIResponseInputToolMCP":
-        """Ensure Authorization header is not passed via headers dict.
-
-        Authorization must be provided via the dedicated 'authorization' parameter
-        to ensure proper security handling and prevent token leakage in responses.
-        """
-        if self.headers:
-            for key in self.headers.keys():
-                if key.lower() == "authorization":
-                    raise ValueError(
-                        "Authorization header cannot be passed via 'headers'. "
-                        "Please use the 'authorization' parameter instead."
-                    )
-        return self
-
 
 OpenAIResponseInputTool = Annotated[
     OpenAIResponseInputToolWebSearch
@@ -625,7 +632,9 @@ class OpenAIResponseObject(BaseModel):
     temperature: float | None = None
     # Default to text format to avoid breaking the loading of old responses
     # before the field was added. New responses will have this set always.
-    text: OpenAIResponseText = OpenAIResponseText(format=OpenAIResponseTextFormat(type="text"))
+    text: OpenAIResponseText = OpenAIResponseText(
+        format=OpenAIResponseTextFormat(type="text")
+    )
     top_p: float | None = None
     tools: Sequence[OpenAIResponseTool] | None = None
     truncation: str | None = None
@@ -804,7 +813,9 @@ class OpenAIResponseObjectStreamResponseFunctionCallArgumentsDelta(BaseModel):
     item_id: str
     output_index: int
     sequence_number: int
-    type: Literal["response.function_call_arguments.delta"] = "response.function_call_arguments.delta"
+    type: Literal["response.function_call_arguments.delta"] = (
+        "response.function_call_arguments.delta"
+    )
 
 
 @json_schema_type
@@ -822,7 +833,9 @@ class OpenAIResponseObjectStreamResponseFunctionCallArgumentsDone(BaseModel):
     item_id: str
     output_index: int
     sequence_number: int
-    type: Literal["response.function_call_arguments.done"] = "response.function_call_arguments.done"
+    type: Literal["response.function_call_arguments.done"] = (
+        "response.function_call_arguments.done"
+    )
 
 
 @json_schema_type
@@ -838,7 +851,9 @@ class OpenAIResponseObjectStreamResponseWebSearchCallInProgress(BaseModel):
     item_id: str
     output_index: int
     sequence_number: int
-    type: Literal["response.web_search_call.in_progress"] = "response.web_search_call.in_progress"
+    type: Literal["response.web_search_call.in_progress"] = (
+        "response.web_search_call.in_progress"
+    )
 
 
 @json_schema_type
@@ -846,7 +861,9 @@ class OpenAIResponseObjectStreamResponseWebSearchCallSearching(BaseModel):
     item_id: str
     output_index: int
     sequence_number: int
-    type: Literal["response.web_search_call.searching"] = "response.web_search_call.searching"
+    type: Literal["response.web_search_call.searching"] = (
+        "response.web_search_call.searching"
+    )
 
 
 @json_schema_type
@@ -862,13 +879,17 @@ class OpenAIResponseObjectStreamResponseWebSearchCallCompleted(BaseModel):
     item_id: str
     output_index: int
     sequence_number: int
-    type: Literal["response.web_search_call.completed"] = "response.web_search_call.completed"
+    type: Literal["response.web_search_call.completed"] = (
+        "response.web_search_call.completed"
+    )
 
 
 @json_schema_type
 class OpenAIResponseObjectStreamResponseMcpListToolsInProgress(BaseModel):
     sequence_number: int
-    type: Literal["response.mcp_list_tools.in_progress"] = "response.mcp_list_tools.in_progress"
+    type: Literal["response.mcp_list_tools.in_progress"] = (
+        "response.mcp_list_tools.in_progress"
+    )
 
 
 @json_schema_type
@@ -880,7 +901,9 @@ class OpenAIResponseObjectStreamResponseMcpListToolsFailed(BaseModel):
 @json_schema_type
 class OpenAIResponseObjectStreamResponseMcpListToolsCompleted(BaseModel):
     sequence_number: int
-    type: Literal["response.mcp_list_tools.completed"] = "response.mcp_list_tools.completed"
+    type: Literal["response.mcp_list_tools.completed"] = (
+        "response.mcp_list_tools.completed"
+    )
 
 
 @json_schema_type
@@ -889,7 +912,9 @@ class OpenAIResponseObjectStreamResponseMcpCallArgumentsDelta(BaseModel):
     item_id: str
     output_index: int
     sequence_number: int
-    type: Literal["response.mcp_call.arguments.delta"] = "response.mcp_call.arguments.delta"
+    type: Literal["response.mcp_call.arguments.delta"] = (
+        "response.mcp_call.arguments.delta"
+    )
 
 
 @json_schema_type
@@ -898,7 +923,9 @@ class OpenAIResponseObjectStreamResponseMcpCallArgumentsDone(BaseModel):
     item_id: str
     output_index: int
     sequence_number: int
-    type: Literal["response.mcp_call.arguments.done"] = "response.mcp_call.arguments.done"
+    type: Literal["response.mcp_call.arguments.done"] = (
+        "response.mcp_call.arguments.done"
+    )
 
 
 @json_schema_type
@@ -970,7 +997,9 @@ class OpenAIResponseContentPartReasoningText(BaseModel):
 
 
 OpenAIResponseContentPart = Annotated[
-    OpenAIResponseContentPartOutputText | OpenAIResponseContentPartRefusal | OpenAIResponseContentPartReasoningText,
+    OpenAIResponseContentPartOutputText
+    | OpenAIResponseContentPartRefusal
+    | OpenAIResponseContentPartReasoningText,
     Field(discriminator="type"),
 ]
 register_schema(OpenAIResponseContentPart, name="OpenAIResponseContentPart")
@@ -1089,7 +1118,9 @@ class OpenAIResponseObjectStreamResponseReasoningSummaryPartAdded(BaseModel):
     part: OpenAIResponseContentPartReasoningSummary
     sequence_number: int
     summary_index: int
-    type: Literal["response.reasoning_summary_part.added"] = "response.reasoning_summary_part.added"
+    type: Literal["response.reasoning_summary_part.added"] = (
+        "response.reasoning_summary_part.added"
+    )
 
 
 @json_schema_type
@@ -1109,7 +1140,9 @@ class OpenAIResponseObjectStreamResponseReasoningSummaryPartDone(BaseModel):
     part: OpenAIResponseContentPartReasoningSummary
     sequence_number: int
     summary_index: int
-    type: Literal["response.reasoning_summary_part.done"] = "response.reasoning_summary_part.done"
+    type: Literal["response.reasoning_summary_part.done"] = (
+        "response.reasoning_summary_part.done"
+    )
 
 
 @json_schema_type
@@ -1129,7 +1162,9 @@ class OpenAIResponseObjectStreamResponseReasoningSummaryTextDelta(BaseModel):
     output_index: int
     sequence_number: int
     summary_index: int
-    type: Literal["response.reasoning_summary_text.delta"] = "response.reasoning_summary_text.delta"
+    type: Literal["response.reasoning_summary_text.delta"] = (
+        "response.reasoning_summary_text.delta"
+    )
 
 
 @json_schema_type
@@ -1149,7 +1184,9 @@ class OpenAIResponseObjectStreamResponseReasoningSummaryTextDone(BaseModel):
     output_index: int
     sequence_number: int
     summary_index: int
-    type: Literal["response.reasoning_summary_text.done"] = "response.reasoning_summary_text.done"
+    type: Literal["response.reasoning_summary_text.done"] = (
+        "response.reasoning_summary_text.done"
+    )
 
 
 @json_schema_type
@@ -1211,7 +1248,9 @@ class OpenAIResponseObjectStreamResponseOutputTextAnnotationAdded(BaseModel):
     annotation_index: int
     annotation: OpenAIResponseAnnotations
     sequence_number: int
-    type: Literal["response.output_text.annotation.added"] = "response.output_text.annotation.added"
+    type: Literal["response.output_text.annotation.added"] = (
+        "response.output_text.annotation.added"
+    )
 
 
 @json_schema_type
@@ -1227,7 +1266,9 @@ class OpenAIResponseObjectStreamResponseFileSearchCallInProgress(BaseModel):
     item_id: str
     output_index: int
     sequence_number: int
-    type: Literal["response.file_search_call.in_progress"] = "response.file_search_call.in_progress"
+    type: Literal["response.file_search_call.in_progress"] = (
+        "response.file_search_call.in_progress"
+    )
 
 
 @json_schema_type
@@ -1243,7 +1284,9 @@ class OpenAIResponseObjectStreamResponseFileSearchCallSearching(BaseModel):
     item_id: str
     output_index: int
     sequence_number: int
-    type: Literal["response.file_search_call.searching"] = "response.file_search_call.searching"
+    type: Literal["response.file_search_call.searching"] = (
+        "response.file_search_call.searching"
+    )
 
 
 @json_schema_type
@@ -1259,7 +1302,9 @@ class OpenAIResponseObjectStreamResponseFileSearchCallCompleted(BaseModel):
     item_id: str
     output_index: int
     sequence_number: int
-    type: Literal["response.file_search_call.completed"] = "response.file_search_call.completed"
+    type: Literal["response.file_search_call.completed"] = (
+        "response.file_search_call.completed"
+    )
 
 
 OpenAIResponseObjectStream = Annotated[
@@ -1350,7 +1395,9 @@ class OpenAIResponseObjectWithInput(OpenAIResponseObject):
 
     def to_response_object(self) -> OpenAIResponseObject:
         """Convert to OpenAIResponseObject by excluding input field."""
-        return OpenAIResponseObject(**{k: v for k, v in self.model_dump().items() if k != "input"})
+        return OpenAIResponseObject(
+            **{k: v for k, v in self.model_dump().items() if k != "input"}
+        )
 
 
 @json_schema_type

src/llama_stack/providers/inline/agents/meta_reference/responses/streaming.py

@@ -1055,6 +1055,15 @@ class StreamingResponseOrchestrator:
         """Process an MCP tool configuration and emit appropriate streaming events."""
         from llama_stack.providers.utils.tools.mcp import list_mcp_tools
 
+        # Validate that Authorization header is not passed via headers dict
+        if mcp_tool.headers:
+            for key in mcp_tool.headers.keys():
+                if key.lower() == "authorization":
+                    raise ValueError(
+                        "Authorization header cannot be passed via 'headers'. "
+                        "Please use the 'authorization' parameter instead."
+                    )
+
         # Emit mcp_list_tools.in_progress
         self.sequence_number += 1
         yield OpenAIResponseObjectStreamResponseMcpListToolsInProgress(