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The AG-UI adapter and middleware enable seamless execution of MCP tools with remote agents (e.g., Python LangGraph, AutoGen, or CopilotKit).

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Installation

npm install @mcp-ts/sdk @ag-ui/client rxjs

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AG-UI Adapter

The AguiAdapter converts MCP tools into the AG-UI protocol format. 
import { MultiSessionClient } from '@mcp-ts/sdk/server';
import { AguiAdapter } from '@mcp-ts/sdk/adapters/agui-adapter';

const client = new MultiSessionClient('user_123');
await client.connect();

const adapter = new AguiAdapter(client);

// Get tools with handlers for server-side execution
const tools = await adapter.getTools();

// Get tool definitions (JSON Schema) for remote agents
const toolDefinitions = await adapter.getToolDefinitions();

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AG-UI Middleware

The AG-UI middleware enables server-side execution of MCP tools. This is essential when your agent runs on a separate backend but needs to execute MCP tools that require server-side access (like database or file system access).

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How It Works

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Usage

import { NextRequest } from "next/server";
import { HttpAgent } from "@ag-ui/client";
import { AguiAdapter } from "@mcp-ts/sdk/adapters/agui-adapter";
import { createMcpMiddleware } from "@mcp-ts/sdk/adapters/agui-middleware";

export const POST = async (req: NextRequest) => {
  // Create remote agent connection
  const mcpAssistant = new HttpAgent({
    url: "http://127.0.0.1:8000/agent",
  });

  // Connect to MCP servers
  const { MultiSessionClient } = await import("@mcp-ts/sdk/server");
  const client = new MultiSessionClient("user_123");
  await client.connect();

  // Create adapter and get tools
  const adapter = new AguiAdapter(client);
  const mcpTools = await adapter.getTools();

  // Add middleware to intercept and execute MCP tools
  mcpAssistant.use(createMcpMiddleware({
    toolPrefix: 'server-',  // Tools starting with this prefix are MCP tools
    tools: mcpTools,
  }));
  
  // Run the agent...
};

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Event Flow

The middleware intercepts AG-UI events and executes MCP tools:
EventDescription
TOOL_CALL_STARTRecords tool name and ID, marks MCP tools as pending
TOOL_CALL_ARGSAccumulates streamed arguments
TOOL_CALL_ENDMarks tool call as complete
RUN_FINISHEDExecutes pending MCP tools, emits results, triggers new run
TOOL_CALL_RESULTEmitted by middleware with MCP tool results

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Configuration Options

createMcpMiddleware({
  toolPrefix: 'server-',  // Prefix to identify MCP tools (default: 'server-')
  tools: mcpTools,        // Pre-loaded tools with handlers
});