Build your own fantasy sports AI agent

import OpenAI from "openai";

const client = new OpenAI();

const response = await client.responses.create({
  model: "YOUR_MODEL",
  input: "Who leads the league, and who plays whom this week?",
  tools: [
    {
      type: "mcp",
      server_label: "league_loom",
      server_url: "https://leagueloom.com/mcp",
      // The token from leagueloom.com/setup, kept in a secret, never in the URL.
      authorization: process.env.LEAGUE_LOOM_TOKEN,
      allowed_tools: ["fantasy_get_standings", "fantasy_get_matchups"],
      require_approval: "never",
    },
  ],
});

console.log(response.output_text);

Replace YOUR_MODEL with a model that supports remote MCP tools. allowed_tools keeps the agent to the league data it needs.

import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic();

const message = await client.beta.messages.create({
  model: "YOUR_MODEL",
  // Tool calls and a full answer share this budget, so leave plenty of room.
  max_tokens: 16000,
  betas: ["mcp-client-2025-11-20"],
  messages: [{ role: "user", content: "Which free agents fit my roster best?" }],
  mcp_servers: [
    {
      type: "url",
      url: "https://leagueloom.com/mcp",
      name: "league_loom",
      authorization_token: process.env.LEAGUE_LOOM_TOKEN,
    },
  ],
  tools: [{ type: "mcp_toolset", mcp_server_name: "league_loom" }],
});

for (const block of message.content) if (block.type === "text") console.log(block.text);

To allow only some tools, set default_config enabled to false on the toolset and enable each tool you want under configs.

import { query } from "@anthropic-ai/claude-agent-sdk";

for await (const message of query({
  prompt: "Write this week's league recap from the standings and matchups.",
  options: {
    mcpServers: {
      league_loom: {
        type: "http",
        url: "https://leagueloom.com/mcp",
        headers: { Authorization: `Bearer ${process.env.LEAGUE_LOOM_TOKEN}` },
      },
    },
    allowedTools: ["mcp__league_loom__fantasy_get_standings", "mcp__league_loom__fantasy_get_matchups"],
  },
})) {
  if (message.type === "result" && message.subtype === "success") console.log(message.result);
}

A wildcard such as mcp__league_loom__* also allows the tool that publishes a shareable league page, so list tools by name if your agent should only read.