Model Context Protocol (MCP)

import { MCPAdapter } from "@langchain/mcp-adapters";
import { createAgent } from "langchain";

async function main() {
  const adapter = new MCPAdapter({
    servers: { docs: { url: "https://docs.langchain.com/mcp" } },
  });

  try {
    const tools = await adapter.listTools();
    const agent = createAgent({ model: "claude-sonnet-5", tools });
    const result = await agent.invoke({
      messages: [
        {
          role: "user",
          content: "How do I add short-term memory to a LangChain agent?",
        },
      ],
    });
    console.log(result.messages.at(-1)?.text);
  } finally {
    await adapter.close();
  }
}

await main();

import { MCPAdapter } from "@langchain/mcp-adapters";

const adapter = new MCPAdapter({
  servers: {
    // A local server launched as a subprocess over stdio.
    local: {
      command: "node",
      args: ["./weather-server.js"],
    },

    // A remote server reached over Streamable HTTP.
    remote: {
      url: "https://example.com/mcp",
    },

    // A legacy server with an explicit SSE endpoint.
    legacy: {
      url: "https://legacy.example.com/sse",
      transport: "sse",
      mode: "legacy",
    },
  },
});

try {
  const tools = await adapter.listTools();
  // Pass tools to createAgent({ tools, ... }).
} finally {
  await adapter.close();
}