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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds genuinely non-obvious behavior: listings are verified on title, photo and price, are live, are scoped to 'today', and each result carries a saving figure and a buy link. That is above what the annotations convey.

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?

A single front-loaded sentence with no filler; the core scope comes first and the parenthetical verification criteria follow. It is dense but every clause adds information, and it could be split slightly for readability.

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?

No output schema exists, so the description's mention of saving and buy link usefully signals return fields, and it explains the deal-eligibility rule an agent needs to interpret results. Pagination and result-size behavior are left to the schema, which is acceptable for a two-parameter read tool.

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 coverage is 100%, with both limit and min_total_usd fully documented including defaults and bounds, so the schema carries parameter meaning. The description contributes no parameter-specific guidance (e.g., that min_total_usd includes shipping is only in the schema), making baseline 3 appropriate.

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?

States a specific resource and scope: curated eBay deals across all cards, with an explicit definition of what makes something a deal (listed below the card's going rate at that grade). It is clearly not a card-specific pricing tool like get_card_prices, though it never names a sibling to sharpen the distinction.

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?

Implies usage ('today's best verified deals' as a browsing/bargain-finding endpoint) but gives no explicit when-to-use versus get_card_prices or get_sales, and no exclusions or prerequisites. The agent must infer that this is a discovery feed rather than a per-card lookup.

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