realtime-crypto-mcp-server/build/tools/getRates.js

A real-time cryptocurrency data provider for Model Context Protocol (MCP) servers. This package integrates with the CoinCap API to provide cryptocurrency exchange details and current rates.

import { z } from "zod";
const COINCAP_API_BASE = "https://api.coincap.io/v2";
// Make API request to CoinCap with rate limiting and retries
async function makeCoinCapRequest(url) {
    const USER_AGENT = "realtime-crypto-app/1.0";
    const MAX_RETRIES = 3;
    const RETRY_DELAY = 1000; // 1 second
    const headers = {
        "User-Agent": USER_AGENT,
        Accept: "application/json",
    };
    let retries = 0;
    while (retries <= MAX_RETRIES) {
        try {
            const response = await fetch(url, { headers });
            if (response.status === 429) {
                // Rate limited - wait and retry
                retries++;
                console.log(`Rate limited by CoinCap API. Retry attempt ${retries}/${MAX_RETRIES} after ${RETRY_DELAY}ms delay`);
                if (retries <= MAX_RETRIES) {
                    await new Promise(resolve => setTimeout(resolve, RETRY_DELAY * retries));
                    continue;
                }
                else {
                    throw new Error("Rate limit exceeded. Maximum retries reached.");
                }
            }
            if (!response.ok) {
                throw new Error(`HTTP error! status: ${response.status}`);
            }
            return (await response.json());
        }
        catch (error) {
            if (retries >= MAX_RETRIES || (error instanceof Error && !error.message.includes("429"))) {
                console.error("Error making CoinCap request:", error);
                return null;
            }
            retries++;
            await new Promise(resolve => setTimeout(resolve, RETRY_DELAY * retries));
        }
    }
    return null;
}
// Format rate details
function formatRateDetails(data) {
    return [
        `Symbol: ${data.symbol || "Unknown"} ${data.currencySymbol || ""}`,
        `Type: ${data.type || "Unknown"}`,
        `USD Rate: $${parseFloat(data.rateUsd).toLocaleString(undefined, { maximumFractionDigits: 2 })}`,
    ].join("\n");
}
// Tool definition for "get-rates"
export const getRatesTool = {
    name: "get-rates",
    description: "Get exchange rates for a cryptocurrency",
    inputSchema: z.object({
        currency: z.string().describe("Cryptocurrency ID (e.g., bitcoin, ethereum, litecoin)"),
    }).shape,
    execute: async (args, extra) => {
        try {
            const currencyId = args.currency.toLowerCase();
            const rateUrl = `${COINCAP_API_BASE}/rates/${currencyId}`;
            const rateData = await makeCoinCapRequest(rateUrl);
            if (!rateData || !rateData.data) {
                return {
                    content: [
                        {
                            type: "text",
                            text: `Failed to retrieve rates for currency: ${currencyId}`,
                        },
                    ],
                };
            }
            const formattedDetails = formatRateDetails(rateData.data);
            const rateText = `Current rate for ${rateData.data.id}:\n\n${formattedDetails}`;
            return {
                content: [
                    {
                        type: "text",
                        text: rateText,
                    },
                ],
            };
        }
        catch (error) {
            console.error("Error in getRatesTool.execute:", error);
            return {
                content: [
                    {
                        type: "text",
                        text: `Error: ${error instanceof Error ? error.message : String(error)}`,
                    },
                ],
                isError: true,
            };
        }
    },
};