Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover the safety profile (readOnlyHint=true, openWorldHint=false), so the bar is lower, and the description adds real behavioral context: median of 3+ sellers, cheapest vs median rate, the 100/70/50/25% of a 730-hour month scenarios, and explicit exclusions. It does not disclose pagination or result-size behavior when scanning all cards.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Information-dense and roughly three sentences, but it opens with a noun-phrase fragment ('A card's new retail price ... against its live on-demand rental rates:') rather than a front-loaded statement of purpose, and the parentheticals make it slower to parse than necessary.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return values needn't be explained, yet the description still spells out the methodology (rate basis, utilization levels, exclusions), which is what an agent needs to interpret the numbers. Nothing critical for correct invocation appears missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% for the single optional gpu parameter, and the description's 'Without gpu, every card that has a retail median' essentially restates the schema's 'omit for every card with a retail median.' No additional syntax or format meaning is contributed, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a precise computation: months of rental (at cheapest and median rate) that equal a card's retail price, at four utilization levels. That is a specific verb+resource and distinguishes it in substance from siblings like gpu_prices or estimate_cost, though it never names an alternative directly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied rather than stated: it is clearly a buy-vs-rent break-even analysis, and the 'Rental fee only - power, hosting, the server around the card and resale are not counted' line implies when NOT to rely on it for total cost of ownership. There is no explicit when-to-use guidance or named alternative (e.g., estimate_cost).

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.