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[MCP] reinject JSON parse & runtime tool errors back into the chat history #3137

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Merged
merged 2 commits into from
Jun 4, 2025
Merged

[MCP] reinject JSON parse & runtime tool errors back into the chat history #3137

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a503c8d
re-inject tool parsing errors into the conversation
hanouticelina Jun 3, 2025
de0ac16
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hanouticelina Jun 3, 2025
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24 changes: 19 additions & 5 deletions src/huggingface_hub/inference/_mcp/mcp_client.py
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Original file line number Diff line number Diff line change
Expand Up @@ -310,7 +310,19 @@ async def process_single_turn_with_tools(
# Process tool calls one by one
for tool_call in final_tool_calls.values():
function_name = tool_call.function.name
function_args = json.loads(tool_call.function.arguments or "{}")
try:
function_args = json.loads(tool_call.function.arguments or "{}")
except json.JSONDecodeError as err:
tool_message = {
"role": "tool",
"tool_call_id": tool_call.id,
"name": function_name,
"content": f"Invalid JSON generated by the model: {err}",
}
tool_message_as_obj = ChatCompletionInputMessage.parse_obj_as_instance(tool_message)
messages.append(tool_message_as_obj)
yield tool_message_as_obj
continue # move to next tool call

tool_message = {"role": "tool", "tool_call_id": tool_call.id, "content": "", "name": function_name}

Expand All @@ -324,11 +336,13 @@ async def process_single_turn_with_tools(
# Execute tool call with the appropriate session
session = self.sessions.get(function_name)
if session is not None:
result = await session.call_tool(function_name, function_args)
tool_message["content"] = format_result(result)
try:
result = await session.call_tool(function_name, function_args)
tool_message["content"] = format_result(result)
except Exception as err:
tool_message["content"] = f"Error: MCP tool call failed with error message: {err}"
Comment on lines +342 to +343
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Copilot AI Jun 3, 2025

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Avoid catching the broad Exception; consider handling specific exceptions thrown by session.call_tool or re-raising unexpected errors to avoid masking serious issues.

Suggested change
except Exception as err:
tool_message["content"] = f"Error: MCP tool call failed with error message: {err}"
except (ValueError, TypeError, json.JSONDecodeError) as err:
tool_message["content"] = f"Error: MCP tool call failed with error message: {err}"
except Exception as err:
logger.error(f"Unexpected error during MCP tool call: {err}")
raise

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@Wauplin Wauplin Jun 3, 2025

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Agree in general but disagree on this specific use case. Let's keep it like this

else:
error_msg = f"Error: No session found for tool: {function_name}"
tool_message["content"] = error_msg
tool_message["content"] = f"Error: No session found for tool: {function_name}"

# Yield tool message
tool_message_as_obj = ChatCompletionInputMessage.parse_obj_as_instance(tool_message)
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