[Frontend] Responses API MCP tools for built in tools and to pass through headers (#24628)

Signed-off-by: Alec Solder <alecs@fb.com>
Signed-off-by: Alec S <10566873+alecsolder@users.noreply.github.com>
Co-authored-by: Alec Solder <alecs@fb.com>
Co-authored-by: Ye (Charlotte) Qi <yeq@meta.com>

vllm/entrypoints/harmony_utils.py

@@ -126,8 +126,10 @@ def get_developer_message(
         function_tools: list[Union[Tool, ChatCompletionToolsParam]] = []
         for tool in tools:
             if tool.type in ("web_search_preview", "code_interpreter",
-                             "container"):
+                             "container", "mcp"):
                 # These are built-in tools that are added to the system message.
+                # Adding in MCP for now until we support MCP tools executed
+                # server side
                 pass
 
             elif tool.type == "function":