Extract tool metadata (ex: tool name) when doing graph.stream(input, stream_mode="messages") ?

[dominpm]

Extract Tool Metadata in graph.stream

When using the graph.stream function with the parameter stream_mode="messages", is it possible to extract metadata associated with the tools being used?. This will include details such as the tool name and other relevant attributes.

I am using the ToolNode to handle tool_llms calls.

Example Usage:

# Example of using graph.stream with stream_mode="messages"
for msg, metadata in graph.stream(input, stream_mode="messages"):
    # Extract tool metadata
    tool_name = metadata.get("tool_name", None) 
    if tool_name:
        print(f"Tool Name: {tool_name}")

Common Use Cases:

• Logging tool usage during streaming.
• Debugging or monitoring which tools are being invoked.
• Building analytics or reports based on tool interactions.

[jedick]

I was also looking for a way to display the tool name during streaming for my application. Printing the entire msg object during execution suggests that the tool name is actually in msg.name, when that's the output of a ToolNode.

This is what worked for me, using LangGraph version 0.4.7 with a graph that has nodes named chatbot and tools. This uses metadata.get("langgraph_node") to get the name of the node, and if that is tools, then looks for the tool name in msg.name.

for msg, metadata in app.stream(inputs, config, stream_mode="messages"):
    # Check for non-empty AI message
    if msg.content and not isinstance(msg, HumanMessage):
        # Adjust output depending on node name
        node_name = metadata.get("langgraph_node", None)
        if node_name == "chatbot":
            # Stream the LLM response
            print(msg.content, end="", flush=True)
        elif node_name == "tools":
            # Check that this is the final output of a tool
            # (not intermediate LLM output from inside a tool)
            if not msg.name is None:
                # Print the tool's name
                print(f"*** Called tool: {msg.name} ***")
        else:
            print(f"Unexpected node name: {node_name}")