Adding a tool

OPENAI_API_KEY=<your-api-key>

import { createTool } from "@mastra/core/tools";
import { z } from "zod";
 
export const londonWeatherTool = createTool({
  id: "london-weather-tool",
  description: "Returns year-to-date historical weather data for London",
  outputSchema: z.object({
    date: z.array(z.string()),
    temp_max: z.array(z.number()),
    temp_min: z.array(z.number()),
    rainfall: z.array(z.number()),
    windspeed: z.array(z.number()),
    snowfall: z.array(z.number())
  }),
  execute: async () => {
    const startDate = `${new Date().getFullYear()}-01-01`;
    const endDate = new Date().toISOString().split("T")[0];
 
    const response = await fetch(
      `https://archive-api.open-meteo.com/v1/archive?latitude=51.5072&longitude=-0.1276&start_date=${startDate}&end_date=${endDate}&daily=temperature_2m_max,temperature_2m_min,precipitation_sum,windspeed_10m_max,snowfall_sum&timezone=auto`
    );
 
    const { daily } = await response.json();
 
    return {
      date: daily.time,
      temp_max: daily.temperature_2m_max,
      temp_min: daily.temperature_2m_min,
      rainfall: daily.precipitation_sum,
      windspeed: daily.windspeed_10m_max,
      snowfall: daily.snowfall_sum
    };
  }
});

import { openai } from "@ai-sdk/openai";
import { Agent } from "@mastra/core/agent";
 
import { londonWeatherTool } from "../tools/example-london-weather-tool";
 
export const londonWeatherAgent = new Agent({
  name: "london-weather-agent",
  description: "Provides historical information about London weather",
  instructions: `You are a helpful assistant with access to historical weather data for London.
    - The data is limited to the current calendar year, from January 1st up to today's date.
    - Use the provided tool (londonWeatherTool) to retrieve relevant data.
    - Answer the user's question using that data.
    - Keep responses concise, factual, and informative.
    - If the question cannot be answered with available data, say so clearly.`,
  model: openai("gpt-4o"),
  tools: { londonWeatherTool }
});

import "dotenv/config";
 
import { mastra } from "./mastra";
 
const agent = mastra.getAgent("londonWeatherAgent");
 
const response = await agent.generate("How many times has it rained this year?");
 
console.log(response.text);