How do I add a fund lookup tool to a Vercel AI SDK chatbot?

Route handler

typescript
// app/api/chat/route.ts — npm install ai @ai-sdk/openai @fundfactsapi/sdk zod
import { openai } from "@ai-sdk/openai";
import { streamText, tool } from "ai";
import { FundFacts } from "@fundfactsapi/sdk";
import { z } from "zod";
​
const ff = new FundFacts({ apiKey: process.env.FUNDFACTS_API_KEY! }); // server only
​
export async function POST(req: Request) {
  const { messages } = await req.json();
  const result = streamText({
    model: openai("gpt-4.1"),
    system: "You answer questions about investment funds using the tools. Always mention asOf with figures; say 'not disclosed' for empty fields.",
    messages,
    tools: {
      fundFacts: tool({
        description: "Current factsheet of a fund or ETF by 12-character ISIN.",
        inputSchema: z.object({ isin: z.string().length(12) }),
        execute: async ({ isin }) => {
          const f = await ff.getFund(isin); // cached in memory until expiresAt
          const d = f.data;
          return {
            name: f.name, category: d.profile.category, risk: d.riskRating, ter: d.headlineMetrics.ter, aum: d.keyFacts.aum,
            topHoldings: d.topHoldings.slice(0, 10), sectors: d.sector.slice(0, 8), countries: d.geography.slice(0, 8),
            calendarReturns: d.calendarReturns, asOf: d.dataAsOf,
          };
        },
      }),
      searchFunds: tool({
        description: "Find ISINs by fund name or issuer. Free.",
        inputSchema: z.object({ query: z.string().min(2) }),
        execute: async ({ query }) => (await ff.search(query)).results.slice(0, 10).map((r) => ({ isin: r.isin, name: r.name, issuer: r.issuer })),
      }),
    },
  });
  return result.toUIMessageStreamResponse();
}

The tool result can be rendered as a card on the client (holdings table, sector donut) with @fundfactsapi/widgets, the same React components that render this site's factsheets.

Or connect the MCP server

The AI SDK can consume MCP tools directly:

typescript
import { experimental_createMCPClient as createMCPClient } from "ai";
​
const mcp = await createMCPClient({
  transport: { type: "http", url: "https://fundfactsapi.com/api/mcp", headers: { Authorization: `Bearer ${process.env.FUNDFACTS_API_KEY}` } },
});
const tools = await mcp.tools(); // get_fund, search_funds, compare_funds, analyze_portfolio, fund_overlap, get_scpi

The MCP server exposes six tools, each counted like the REST endpoint it wraps: get_fund (ISIN → the full factsheet payload), search_funds (name → ISINs, free), compare_funds (side-by-side table for several ISINs), analyze_portfolio (weighted look-through of a list of positions, Pro and above), fund_overlap (shared holdings between funds, Pro and above) and get_scpi (French SCPI data by name or ISIN). Authentication is the same bearer API key as the REST API, sent as an Authorization header.

Notes

• A cold ISIN can take minutes on first load; set maxDuration on the route accordingly or pre-warm the funds your users ask about.
• One request per ISIN answered; the SDK client caches until expiresAt so repeated questions in a session cost nothing extra.
• Never call the API from the browser; the key belongs in the route handler.