MultipleSubgraphsError

[Bayleaf2]

I have an agent that invokes a tool multiple times in parallel. The tool itself uses an agent, hence the error. While I understand why I'm receiving this error, I'm at a loss as to a workaround. I've read in another thread that this is not an issue if the parent agent has no checkpointer, but my application requires that it does.

Basically what I'm trying to do is create a react agent with tools that themselves invoke react agents with tools. Is there way of accomplishing this?

[vbarda]

@Bayleaf2 could you please provide a reproducible code example?

[Bayleaf2]

I have found a temporary workaround, though it's not a very desirable one. I wrote my own react agent, not using Langgraph, that is used inside the tool. This seems to work, which would seem to suggest there's a Langgraph limitation? In any case, I'd prefer to use Langgraph for all my agents if possible.

[Bayleaf2]

It looks like I spoke too soon, my workaround has introduced new issues.

In short, I'm using a React agent that has tools, and these tools can also use React agents with their own tools. It's straightforward, but is what I'm trying to achieve technically unreasonable or unfeasible?

[ImadSaddik]

I ran into the same issue as you.

[ImadSaddik]

I have one agent that interacts with the tool node, inside the tool I have 3 tools, in each one of those tools I have a sub agent. The first query does not trigger the exception, but once I try to ask a follow-up question, I get that error.

[hinthornw]

Two ways to handle this:

1. You can turn checkpointing off on the subgraph (.compile(checkpointer=False)) to permit multiple subgraphs
2. If you still need checkpointing for things like HITL, then you can use regular langgraph branching rather than using the tool node in isolation. Silly example below:

async def my_llm_call(state):
    ai_msg =  await llm.invoke(...)
    sends = []
    if ai_msg.tool_calls:
        for tc in ai_msg.tool_calls:
            cp = ai_msg.copy()
            cp.tool_calls = [tc]
            sends.append(Send({"messages": [cp]}))
            
    return Command(sends=sends)