TypeError: cannot pickle '_asyncio.Future' object when using Playwright MCP server with LangChain adapter and Ollama

[fahad-charolia]

Getting a serialization error when trying to use the Playwright MCP server with the LangChain adapter. The error occurs during tool creation when the library attempts to deep copy objects containing asyncio Future objects.

Error Message
TypeError: cannot pickle '_asyncio.Future' object

Environment
Python: 3.11.5
OS: Windows
mcp-use: 1.3.10
langchain: 0.3.5
langchain-core: 0.3.13
langchain_ollama: 0.2.0
pydantic: 2.7.4
pydantic-settings: 2.10.1

Code to reproduce

import asyncio
from dotenv import load_dotenv
from langchain_ollama import ChatOllama
from mcp_use import MCPAgent, MCPClient

async def main():
    load_dotenv()

    config = {
        "mcpServers": {
            "playwright": {
                "command": "npx",
                "args": ["@playwright/mcp@latest"],
                "env": {
                    "DISPLAY": ":1"
                }
            }
        }
    }

    client = MCPClient.from_dict(config)
    llm = ChatOllama(model="gpt-oss:20b")
    agent = MCPAgent(llm=llm, client=client, max_steps=30)

    result = await agent.run("Go to google.com and search for 'LangChain'")
    print(f"\nResult: {result}")

if __name__ == "__main__":
    asyncio.run(main())