Does the description clearly state what the tool does and how it differs from similar tools?
Description states a specific action ('Returns the biggest 30-day gainers or drops'), names the resource ('trending cards'), and gives clear trigger phrasing ('rising, hot, spiking, crashing or trending'). It also excludes single-card and long-term-history use cases, which distinguishes it from get_card_prices and get_price_history.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.