[GPT-OSS] Add support for arrays at tool message content (#25593)

Signed-off-by: Luis Tomas Bolivar <ltomasbo@redhat.com>

vllm/entrypoints/harmony_utils.py

@@ -256,6 +256,13 @@ def parse_chat_input(chat_msg) -> list[Message]:
     if role == "tool":
         name = chat_msg.get("name", "")
         content = chat_msg.get("content", "") or ""
+        if isinstance(content, list):
+            # Handle array format for tool message content
+            # by concatenating all text parts.
+            content = "".join(
+                item.get("text", "") for item in content
+                if isinstance(item, dict) and item.get("type") == "text")
+
         msg = Message.from_author_and_content(
             Author.new(Role.TOOL, f"functions.{name}"), content
         ).with_channel("commentary")