AI Message Compilation Error with Tool Call and List Content

[AustinJiangH]

There is a chance that the model returns an AI message with the content being a list, AIMessage(content=[], tool_calls=[...]).

When involving this message in the conversation, the tool calls gets trimmed out. It runs into the if block on line 83 because the content type is list and never gets into the elif block for the tool call on line 141.

langchain-google/libs/vertexai/langchain_google_vertexai/_anthropic_utils.py

Lines 83 to 141 in af44de3

	if not isinstance(message.content, str):
	# parse as dict
	assert isinstance(
	message.content, list
	), "Anthropic message content must be str or list of dicts"
	# populate content
	content = []
	for item in message.content:
	if isinstance(item, str):
	content.append(
	{
	"type": "text",
	"text": item,
	}
	)
	elif isinstance(item, dict):
	if "type" not in item:
	raise ValueError("Dict content item must have a type key")
	elif item["type"] == "image_url":
	# convert format
	source = _format_image(item["image_url"]["url"])
	content.append(
	{
	"type": "image",
	"source": source,
	}
	)
	elif item["type"] == "tool_use":
	# If a tool_call with the same id as a tool_use content block
	# exists, the tool_call is preferred.
	if isinstance(message, AIMessage) and item["id"] in [
	tc["id"] for tc in message.tool_calls
	]:
	overlapping = [
	tc
	for tc in message.tool_calls
	if tc["id"] == item["id"]
	]
	content.extend(
	_lc_tool_calls_to_anthropic_tool_use_blocks(overlapping)
	)
	else:
	item.pop("text", None)
	content.append(item)
	elif item["type"] == "text":
	text = item.get("text", "")
	# Only add non-empty strings for now as empty ones are not
	# accepted.
	# https://github.com/anthropics/anthropic-sdk-python/issues/461
	if text.strip():
	content.append({"type": "text", "text": text})
	else:
	content.append(item)
	else:
	raise ValueError(
	f"Content items must be str or dict, instead was: {type(item)}"
	)
	elif isinstance(message, AIMessage) and message.tool_calls:

This will eventually get into a bad request error.

Error code: 400 - {'type': 'error', 'error': {'type': 'invalid_request_error', 'message': 'messages.2: `tool_result` block(s) provided when previous message does not contain any `tool_use` blocks'}}

[lkuligin]

thanks for spotting this!

would you be open to send a PR with a fix (and ideally also add a unit test for this case)?