issues when using an agent with a MCP server with create_supervisor

[jonathanbouchet]

Hi,
I would like to create a supervisor agent (using create_supervisor library) where there are 2 agents (using create_react_agent) with some basic tools, and another agent having a MCP server

agents with tools

# create tools
def add(a: float, b: float) -> float:
    """Add two numbers."""
    return a + b


def multiply(a: float, b: float) -> float:
    """Multiply two numbers."""
    return a * b

def get_weather(location: str):
    """Call to get the current weather."""
    if location.lower() == "seattle":
        return f"It's 15 degrees Celsius and cloudy in {location}."
    else:
        return f"It's 32 degrees Celsius and sunny in {location}."

# create sub-agents
math_agent = create_react_agent(
    model=model,
    tools=[add, multiply],
    name="math_expert",
    prompt=MATH_PROMPT
)

weather_agent = create_react_agent(
    model=model,
    tools=[get_weather],
    name="weather_expert",
    prompt=WEATHER_PROMPT
)

agent with mcp server

• from src/mcp_agent.py

async def another_agent():
    mcp_client = MultiServerMCPClient(
        {
            ...
            "transport": "sse"
            },
        }
    )
    mcp_tools = await mcp_client.get_tools()
    another_agent = create_react_agent(
        model=model, 
        tools=mcp_tools,
        prompt=PROMPT,
        name="another_agent"
    )
    return another_agent

main file

Then I make the supervisor with the following:

from src/mcp_agent.py import another_agent
supervisor = create_supervisor(
    [math_agent, weather_agent, another_agent],
    model=model,
    prompt=SUPERVISOR_PROMPT
).compile(
)

However I'm having the following issue:

supervisor = create_supervisor(
                 ^^^^^^^^^^^^^^^^^^
  File "/Users/jonathan/Documents/WORK/langgraph-chat/.venv/lib/python3.12/site-packages/langgraph_supervisor/supervisor.py", line 372, in create_supervisor
    if [agent.name](http://agent.name/) is None or [agent.name](http://agent.name/) == "LangGraph":
       ^^^^^^^^^^
AttributeError: 'function' object has no attribute 'name'

I've been trying several ways to include the another_agent (using @asynccontextmanager) but still got an issue when adding this specific agent to the supervisor.

Any help would be appreciated.
Thanks in advance.

---

langchain 0.3.25
langchain-core 0.3.64
langchain-mcp-adapters 0.1.7
langchain-openai 0.3.21
langchain-text-splitters 0.3.8
langgraph 0.4.8
langgraph-api 0.2.63
langgraph-checkpoint 2.0.26
langgraph-cli 0.3.3
langgraph-prebuilt 0.2.2
langgraph-runtime-inmem 0.3.2
langgraph-sdk 0.1.70
langgraph-supervisor 0.0.27
langsmith 0.3.45
mcp 1.9.4

Python 3.12.10

[jdeepaa]

another_agent() function has to be called first to get the agent and then pass it in create_supervisor. Did you do that?