at-mintel/packages/payload-ai/src/tools/mcpAdapter.ts

import { Client } from "@modelcontextprotocol/sdk/client/index.js";
import { SSEClientTransport } from "@modelcontextprotocol/sdk/client/sse.js";
import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js";
import { tool, jsonSchema } from "ai";
/**
 * Connects to an external MCP Server and maps its tools to Vercel AI SDK Tools.
 */
export async function createMcpTools(mcpConfig: {
  name: string;
  url?: string;
  command?: string;
  args?: string[];
}) {
  let transport;

  // Support both HTTP/SSE and STDIO transports
  if (mcpConfig.url) {
    transport = new SSEClientTransport(new URL(mcpConfig.url));
  } else if (mcpConfig.command) {
    transport = new StdioClientTransport({
      command: mcpConfig.command,
      args: mcpConfig.args || [],
    });
  } else {
    throw new Error("Invalid MCP config: Must provide either URL or Command.");
  }

  const client = new Client(
    { name: `payload-ai-client-${mcpConfig.name}`, version: "1.0.0" },
    { capabilities: {} },
  );

  await client.connect(transport);

  // Fetch available tools from the external MCP server
  const toolListResult = await client.listTools();
  const externalTools = toolListResult.tools || [];

  const aiSdkTools: Record<string, any> = {};

  // Map each external tool to a Vercel AI SDK Tool
  for (const extTool of externalTools) {
    // Basic conversion of JSON Schema to Zod for the AI SDK
    // Note: For a production ready adapter, you might need a more robust jsonSchemaToZod converter
    // or use AI SDK's new experimental generateSchema feature if available.
    // Here we use a generic `z.any()` as a fallback since AI SDK requires a Zod schema.
    const toolSchema = extTool.inputSchema as Record<string, any>;

    // We create a simplified parameter parser.
    // An ideal approach uses `jsonSchemaToZod` library or native AI SDK JSON schema support
    // (introduced recently in `ai` package).

    aiSdkTools[`${mcpConfig.name}_${extTool.name}`] = tool({
      description: `[From ${mcpConfig.name}] ${extTool.description || extTool.name}`,
      parameters: jsonSchema(toolSchema as any),
      // @ts-expect-error - AI strict mode overload bug with implicit zod inferences
      execute: async (args: any) => {
        const result = await client.callTool({
          name: extTool.name,
          arguments: args,
        });
        return result;
      },
    });
  }

  return { tools: aiSdkTools, client };
}