Stock Prices

Query real-time stock prices and market data using the Stock Prices API. Responses are in TOON format—decode with @toon-format/toon. Use when fetching stock...

Security Scan

The skill's requests and runtime instructions are consistent with its stated purpose (fetching stock quotes); it does not ask for credentials or broad system access and contains no install-time surprises, but you should still verify the third-party API domain and the TOON npm package before use.

Purpose & Capability

Name/description, API base URL, endpoints, example requests, and decoding instructions all align with a stock-quote retrieval skill. There are no declared env vars, binaries, or config paths that are unrelated to fetching or decoding quotes.

Instruction Scope

SKILL.md only instructs the agent to call the provided HTTPS endpoint and decode the TOON response with an npm package; it does not direct access to unrelated files, environment variables, or external endpoints beyond the described API and the suggested decoder.

Install Mechanism

The skill is instruction-only (no install spec), which is low-risk. It suggests installing @toon-format/toon via pnpm for decoding; this is reasonable for the stated purpose but is an external package so verify its provenance before installing in environments with strict supply-chain requirements.

Credentials

The skill requests no environment variables, credentials, or config paths. This is proportionate to a public-stock-quote fetcher that does not advertise authenticated endpoints.

Persistence & Privilege

The skill does not request persistent/always-on privilege and uses default invocation settings. It does not instruct modifying other skills or system-wide settings.

Assessment

This skill appears coherent and limited to fetching and decoding stock data. Before installing or using it, verify two things: (1) the API host (https://stock-prices.on99.app) — confirm you trust the operator, check HTTPS/TLS and any privacy or rate-limit policies; (2) the npm package @toon-format/toon — inspect the package source, maintainers, and download counts to ensure it's legitimate. If you plan to use this with private or sensitive data, consider whether the API requires/authenticates requests and avoid embedding secrets in plain query strings. If you need guaranteed provenance, prefer an official/known data provider or self-host a vetted decoder implementation.

Stock Prices API Skill

This skill helps you work with the Stock Prices API to fetch real-time market data and stock quotes.

API Endpoint

Base URL: https://stock-prices.on99.app

Primary Endpoint: /quotes?symbols={SYMBOLS}

Quick Start

Fetch stock quotes for one or more symbols (responses are in TOON format):

curl "https://stock-prices.on99.app/quotes?symbols=NVDA"
curl "https://stock-prices.on99.app/quotes?symbols=AAPL,GOOGL,MSFT"

Install the TOON decoder for parsing: pnpm add @toon-format/toon

Response Format

The API returns TOON (Token-Oriented Object Notation) format—a compact, human-readable encoding that uses ~40% fewer tokens than JSON. This makes it ideal for LLM prompts and streaming.

TOON Response Example

quotes[1]{symbol,currentPrice,change,percentChange,highPrice,lowPrice,openPrice,previousClosePrice,preMarketPrice,preMarketChange,preMarketTime,preMarketChangePercent,...}:
  NVDA,188.54,-1.5,-0.789308,192.48,188.12,191.405,190.04,191.8799,3.3399048,2026-02-11T13:49:16.000Z,1.771457,...

Decoding TOON Responses

Use @toon-format/toon to parse responses back to JavaScript/JSON:

import { decode } from "@toon-format/toon";

const response = await fetch("https://stock-prices.on99.app/quotes?symbols=NVDA");
const toonText = await response.text();
const data = decode(toonText);

// data.quotes is an array of quote objects
const quote = data.quotes[0];
console.log(`${quote.symbol}: $${quote.currentPrice}`);

The decoded structure matches JSON—same objects, arrays, and primitives.

Available Data Fields

Field	Type	Description
symbol	string	Stock ticker symbol
currentPrice	number	Current trading price
change	number	Price change from previous close
percentChange	number	Percentage change from previous close
highPrice	number	Day's high price
lowPrice	number	Day's low price
openPrice	number	Opening price
previousClosePrice	number	Previous day's closing price
preMarketPrice	number	Pre-market trading price
preMarketChange	number	Pre-market price change
preMarketTime	string (ISO 8601)	Pre-market data timestamp
preMarketChangePercent	number	Pre-market percentage change

Usage Guidelines

Multiple Symbols

Query multiple stocks by separating symbols with commas (max 50):

curl "https://stock-prices.on99.app/quotes?symbols=AAPL,GOOGL,MSFT,TSLA,AMZN"

Error Handling

Always check for valid responses. Decode TOON before accessing data:

import { decode } from "@toon-format/toon";

const response = await fetch("https://stock-prices.on99.app/quotes?symbols=NVDA");
const data = decode(await response.text());

if (data.quotes && data.quotes.length > 0) {
    const quote = data.quotes[0];
    console.log(`${quote.symbol}: $${quote.currentPrice}`);
}

Price Analysis

Calculate common metrics:

// Determine if stock is up or down
const isUp = quote.change > 0;
const direction = isUp ? "📈" : "📉";

// Calculate day's range percentage
const rangePct = ((quote.highPrice - quote.lowPrice) / quote.lowPrice) * 100;

// Compare current to open
const vsOpen = quote.currentPrice - quote.openPrice;

Common Use Cases

1. Price Monitoring

import { decode } from "@toon-format/toon";

async function checkPrice(symbol: string) {
    const res = await fetch(`https://stock-prices.on99.app/quotes?symbols=${symbol}`);
    const data = decode(await res.text());
    const quote = data.quotes[0];

    return {
        price: quote.currentPrice,
        change: quote.change,
        changePercent: quote.percentChange,
    };
}

2. Portfolio Tracking

import { decode } from "@toon-format/toon";

async function getPortfolio(symbols: string[]) {
    const symbolString = symbols.join(",");
    const res = await fetch(`https://stock-prices.on99.app/quotes?symbols=${symbolString}`);
    const data = decode(await res.text());

    return data.quotes.map(q => ({
        symbol: q.symbol,
        value: q.currentPrice,
        dailyChange: q.percentChange,
    }));
}

3. Market Summary

import { decode } from "@toon-format/toon";

async function marketSummary(symbols: string[]) {
    const res = await fetch(`https://stock-prices.on99.app/quotes?symbols=${symbols.join(",")}`);
    const data = decode(await res.text());

    const gainers = data.quotes.filter(q => q.change > 0);
    const losers = data.quotes.filter(q => q.change < 0);

    return {
        totalStocks: data.quotes.length,
        gainers: gainers.length,
        losers: losers.length,
        avgChange: data.quotes.reduce((sum, q) => sum + q.percentChange, 0) / data.quotes.length,
    };
}

Popular Stock Symbols

Tech Giants (FAANG+)

• AAPL - Apple
• GOOGL - Alphabet (Google)
• META - Meta (Facebook)
• AMZN - Amazon
• NFLX - Netflix
• MSFT - Microsoft

High-Profile Stocks

• NVDA - NVIDIA
• TSLA - Tesla
• AMD - Advanced Micro Devices
• INTC - Intel
• ORCL - Oracle

Indices

• ^GSPC - S&P 500
• ^DJI - Dow Jones
• ^IXIC - NASDAQ

Notes

• Response format: API returns TOON, not JSON. Use decode() from @toon-format/toon to parse.
• All prices are in USD
• Data updates in real-time during market hours
• Pre-market and after-hours data is available
• Timestamps are in ISO 8601 format (UTC)
• Maximum 50 symbols per request