HELP：tool event missing "toolCallId" when tool return Command

LangChain Academy
1

copilotkit raise error:

[ { “code”: “invalid_type”, “expected”: “string”, “received”: “undefined”, “path”: [ “toolCallId” ], “message”: “Required” }, { “code”: “invalid_type”, “expected”: “string”, “received”: “undefined”, “path”: [ “toolCallName” ], “message”: “Required” } ]

langchain tool:

@tool(description="更新todolist")
def write_todos(
    todos: list[Todo], tool_call_id: Annotated[str, InjectedToolCallId]
) -> Command:
    """Create and manage a structured task list for your current work session."""
    # it it ok if return tool message
    # return ToolMessage(f"Updated todo list to {todos}", tool_call_id=tool_call_id, name="write_todos") 
    return Command(
        update={
            "todos": todos,
            "messages": [
                ToolMessage(f"Updated todo list to {todos}", tool_call_id=tool_call_id, name="write_todos")
            ],
        }
    )
2

hi @itzhoujun

can you share some more code? What’s the provider?

3

hi @pawel-twardziak

it is ok if the tool return ToolMessage, and will be error when return Command

my full code:


from os import name
from copilotkit import CopilotKitState
from langchain_openai import ChatOpenAI
from langchain.agents import create_agent
from typing import TYPE_CHECKING, Annotated, Literal, cast
from settings import settings
from src.utils import load_prompt
from langgraph.types import Command
from langchain.tools import InjectedToolCallId
from langchain_core.messages import SystemMessage, ToolMessage
from langchain_core.tools import tool
from langchain.agents.middleware.todo import Todo

@tool(description="更新todolist")
def write_todos(
    todos: list[Todo], tool_call_id: Annotated[str, InjectedToolCallId]
) -> Command:
    """Create and manage a structured task list for your current work session."""
    # it is ok if return ToolMessage
    # return ToolMessage(f"Updated todo list to {todos}", tool_call_id=tool_call_id, name="write_todos")
    return Command(
        update={
            "todos": todos,
            "messages": [
                ToolMessage(f"Updated todo list to {todos}", tool_call_id=tool_call_id, name="write_todos")
            ],
        }
    )
    
def create_demo_agent():
    """
    创建 Demo Agent 实例。
    
    这是一个通用的助手 Agent，可以处理各种用户请求和对话。
    
    Returns:
        LangChain Agent 实例
    """
    model = ChatOpenAI(
        model=settings.openai_model,
        base_url=settings.openai_base_url,
        api_key=settings.openai_api_key,
        temperature=0.7,  # 适中的温度以保持友好和灵活性
    )
    system_prompt = load_prompt("demo_agent_system.md")
    
    agent = create_agent(
        model=model,
        system_prompt=system_prompt,
        tools=[write_todos]
    )
    return agent


# 创建默认 agent 实例
agent = create_demo_agent()

copilokit error stack：

image
image2752×636 144 KB

I guess that agui protocol require tool_call_id in TOOL_CALL_START but langgraph miss it
ref: Events - Agent User Interaction Protocol

4

do you use LangGraphAgent from CopilotKit SDK?

5

yes. I’m using LangGraphAgent as Copilot Runtime

6

Seems like CopilotKit LangGraphAgent doesn’t handle Command as tool response for now.

Return a normal tool result (ToolMessage or plain string), and move state updates (todos) into a graph node (or a post-tool node) instead of doing state updates inside the tool return.

One robust pattern is:

  • Tool returns a ToolMessage (optionally put structured data in artifact or JSON in content).
  • A “post-tools” node inspects the last ToolMessage and updates state["todos"].
ToolMessage(
            content=tool_output["stdout"],
            artifact=tool_output,
            tool_call_id="call_Jja7J89XsjrOLA5r!MEOW!SL",
        )

This keeps CopilotKit happy because it always sees a standard tool result (ToolMessage) with a valid tool_call_id.

7

@itzhoujun could you try to patch your local installed copilotkit package? I can provide you with a patch so that we can see whether it works. If it does, I could raise a PR.

And what is the version of copilotkit you are using? The latest?

8

Thank you very much, my copilotkit version is 1.50.1, can you send the patch package to my mailbox? itzhoujun@gmail.com
I set the ToolMessage.artifact to todos , and then how to update it to the state?

9

To update it in the state you would have to skip create_agent in favor of a custom graph.
I’ll send the patch here, in the thread.

10

hi @itzhoujun are you on Langchain Slack?

11

I’ve just raised a PR fix(runtime): ensure toolCallId and toolCallName in LangGraph agent by pawel-twardziak · Pull Request #2904 · CopilotKit/CopilotKit · GitHub

12

thanks :growing_heart: