mcp-use - The fullstack MCP framework to develop MCP Apps for ChatGPT / Claude and MCP Servers for AI Agents.

Server Manager gives LangChainMCPAgent management tools first, then exposes the active MCP server’s tools after the model selects a server. Use it when loading every tool from every configured server would create an oversized or confusing tool list.

Enable Server Manager

Server Manager requires explicit mode with an MCPClient. It cannot run with connectors alone.

import { ChatOpenAI } from "@langchain/openai";
import { MCPClient } from "@mcp-use/client";
import { LangChainMCPAgent } from "@mcp-use/agent/langchain";

async function main() {
  const client = new MCPClient({
    mcpServers: {
      filesystem: {
        command: "npx",
        args: ["-y", "@modelcontextprotocol/server-filesystem", "/tmp"],
      },
      browser: {
        command: "npx",
        args: ["@playwright/mcp@latest"],
      },
    },
  });

  const agent = new LangChainMCPAgent({
    llm: new ChatOpenAI({ model: "gpt-4o", temperature: 0 }),
    client,
    useServerManager: true,
    maxSteps: 12,
  });

  try {
    await agent.initialize();
    const result = await agent.run({
      prompt:
        "List the available MCP servers, select the filesystem server, and summarize /tmp.",
    });
    console.log(result);
  } finally {
    await agent.close();
  }
}

main().catch(console.error);

A successful run lists the configured servers, activates filesystem, and uses its tools. The agent rebuilds its LangChain executor when the active tool set changes.

Understand the management tools

Tool	Behavior
`list_mcp_servers`	Lists configured server names and cached item counts. Counts can be zero before tools are loaded or prefetched.
`connect_to_mcp_server`	Reuses or creates a session, activates the server, and loads its tools, resources, and prompts when not cached.
`get_active_mcp_server`	Reports the selected active server without changing it.
`disconnect_from_mcp_server`	Releases the active selection so its cached tools are no longer exposed.
`add_mcp_server_from_config`	Adds a server, creates its session, loads its tools, and makes it active.

Only one server is active at a time. The five management tools remain available alongside the active server’s cached tools.

add_mcp_server_from_config loads tools only. connect_to_mcp_server loads tools, resources, and prompts when it first caches a configured server.

Release a server without closing its session

Despite its tool name, disconnect_from_mcp_server does not close the underlying MCP session. It sets the active server to null; the session and cached tools remain available for later selection. Use await agent.close() to finish the agent lifecycle. LangChainMCPAgent shuts down observability, clears its executor and tools, and closes the MCPClient sessions.

Customize the manager

Import ServerManager and LangChainAdapter from the LangChain subpath. Use serverManagerFactory when you need to prefetch tools or provide a custom manager instance.

import {
  LangChainAdapter,
  LangChainMCPAgent,
  ServerManager,
} from "@mcp-use/agent/langchain";

const agent = new LangChainMCPAgent({
  llm,
  client,
  useServerManager: true,
  serverManagerFactory: (managerClient) => {
    const adapter = new LangChainAdapter();
    return new ServerManager(managerClient, adapter);
  },
});

await agent.initialize();
await agent.close();

prefetchServerTools() caches tools, resources, and prompts for configured servers. It can create sessions and leaves those sessions open until client cleanup.

Know when to skip it

For one or two small servers, load tools normally. Server Manager adds a model decision before the first server tool call and can restart execution when the exposed tool set changes.

Get Started

MCP Server

MCP Apps

MCP Client

MCP Agent

Tooling

Server Manager

Enable Server Manager

Understand the management tools

Release a server without closing its session

Customize the manager

Know when to skip it

Next steps

​Enable Server Manager

​Understand the management tools

​Release a server without closing its session

​Customize the manager

​Know when to skip it

​Next steps

Enable Server Manager

Understand the management tools

Release a server without closing its session

Customize the manager

Know when to skip it

Next steps