market_cap
Retrieve top cryptocurrencies by market cap, including current prices, trading volumes, and 24-hour percentage changes.
Instructions
Get top cryptocurrencies ranked by market cap with prices, volumes, and 24h changes.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | Number of coins to return (default: 20, max: 100) |
Implementation Reference
- index.js:122-135 (handler)The main handler function `getMarketCap(limit)` that fetches top coins by market cap from CoinGecko API and returns an array of ranked coin data (rank, symbol, name, price, market_cap, volume_24h, change_24h).
async function getMarketCap(limit = 20) { const data = await fetch( `https://api.coingecko.com/api/v3/coins/markets?vs_currency=usd&order=market_cap_desc&per_page=${limit}&page=1&sparkline=false` ); return data.map((c, i) => ({ rank: i + 1, symbol: c.symbol.toUpperCase(), name: c.name, price: c.current_price, market_cap: c.market_cap, volume_24h: c.total_volume, change_24h: c.price_change_percentage_24h, })); } - index.js:272-281 (schema)Tool definition for 'market_cap' including its name, description, and inputSchema (accepts optional 'limit' parameter, default 20, max 100).
{ name: 'market_cap', description: 'Get top cryptocurrencies ranked by market cap with prices, volumes, and 24h changes.', inputSchema: { type: 'object', properties: { limit: { type: 'number', description: 'Number of coins to return (default: 20, max: 100)' } } } }, - index.js:329-330 (registration)Handler dispatch in `handleToolCall` — routes the 'market_cap' case to `getMarketCap`, clamping limit to max 100.
case 'market_cap': return await getMarketCap(Math.min(args.limit || 20, 100)); - index.js:31-44 (helper)The `fetch(url)` helper function used by `getMarketCap` to make HTTPS requests to the CoinGecko API.
function fetch(url) { return new Promise((resolve, reject) => { const req = https.get(url, { headers: { 'User-Agent': 'mcp-market-data/0.1' } }, (res) => { let data = ''; res.on('data', chunk => data += chunk); res.on('end', () => { try { resolve(JSON.parse(data)); } catch (e) { reject(new Error(`Parse error: ${data.slice(0, 200)}`)); } }); }); req.on('error', reject); req.setTimeout(15000, () => { req.destroy(); reject(new Error('Timeout')); }); }); }