fix(responses): match guardrail tools by ordinal in one pass

Sort the chat-tool keys once and number duplicates with groupby instead of
rescanning every preceding key per position, so the guardrail merge stays
O(n log n) on client-supplied tool lists. Drop the comment that restated the
unsupported-tool warning in the Responses-to-chat transformation.

litellm/llms/openai/responses/guardrail_translation/tool_merge.py

@@ -1,5 +1,5 @@
 from collections.abc import Iterable, Mapping, Sequence
-from itertools import accumulate, chain
+from itertools import accumulate, chain, groupby
 from types import MappingProxyType
 from typing import Final, TypeAlias
 
@@ -47,7 +47,11 @@ def _chat_tool_key(tool: Tool) -> str:
 
 def _indexed_keys(tools: Sequence[Tool]) -> tuple[IndexedKey, ...]:
     keys: Final = tuple(_chat_tool_key(tool) for tool in tools)
-    return tuple((key, keys[:position].count(key)) for position, key in enumerate(keys))
+    positions_by_key: Final = groupby(sorted(range(len(keys)), key=keys.__getitem__), key=keys.__getitem__)
+    ordinal_by_position: Final = MappingProxyType(
+        {position: ordinal for _, positions in positions_by_key for ordinal, position in enumerate(positions)}
+    )
+    return tuple((key, ordinal_by_position[position]) for position, key in enumerate(keys))
 
 
 def _namespace_members(namespace: Tool) -> tuple[Tool, ...]:

litellm/responses/litellm_completion_transformation/transformation.py

@@ -1903,10 +1903,6 @@ class LiteLLMCompletionResponsesConfig:
             converted: Final = convert_custom_tool_to_function_tool(tool)
             return ResponsesToolChatForm(chat_tools=() if converted is None else (converted,), web_search_options=None)
         if tool_type in ("computer_use", "image_generation", "shell"):
-            # Drop unsupported Responses-API-only tool types that have no
-            # Chat Completions equivalent. Passing them through verbatim
-            # causes providers to reject the request with "'function' is a
-            # required property".
             verbose_logger.warning(
                 "Dropping Responses API tool of type '%s': it has no Chat Completions "
                 "equivalent and the target provider would reject the request.",

tests/test_litellm/llms/openai/responses/test_openai_responses_guardrail_tool_merge.py

@@ -56,6 +56,24 @@ def test_duplicate_function_names_are_matched_by_ordinal():
     assert list(merged) == [original[0]]
 
 
+def test_interleaved_duplicate_names_keep_their_own_ordinals():
+    original = [
+        _function("dup", "a"),
+        _function("other", "x"),
+        _function("dup", "b"),
+        _function("dup", "c"),
+        _function("other", "y"),
+    ]
+    groups = _groups(original)
+    flat = _flat(groups)
+    edited = {**flat[3], "function": {**flat[3]["function"], "description": "changed"}}
+
+    merged = merge_guardrailed_tools(original, groups, [*flat[:3], edited, flat[4]])
+
+    assert list(merged) == [*original[:3], {**_function("dup", "changed"), "strict": False}, original[4]]
+    assert all(merged[position] is original[position] for position in (0, 1, 2, 4))
+
+
 def test_edited_mcp_tool_is_rewritten():
     original = [{"type": "mcp", "server_label": "deepwiki", "server_url": "https://mcp.deepwiki.com/mcp"}]
     groups = _groups(original)