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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds behavior not in the annotations: currency (USD), the 30-day percent-change metric, and the most-expensive-first sort order. It doesn't say what happens when limit is omitted or how the list is paginated, which keeps it from a 5.

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?

Three sentences with no waste: the trigger comes first, then the return shape, then the alternative. Each sentence carries distinct information an agent needs.

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?

Output schema exists, so return values needn't be re-explained, and the game enum plus limit range are fully documented in the schema. What remains thin is list-size/pagination behavior at the default limit, a minor gap for a simple 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 description coverage is 100% with an enum on game and a documented limit range, so the schema carries the parameter burden. The description only echoes 'one game' and implies ordering; it adds no format or tuning guidance beyond structured fields. Baseline 3 is 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?

Specific verb+resource with clear scope: sealed product prices for one game, with the product categories (booster boxes, ETBs, bundles, packs, tins, cases) enumerated so the agent knows exactly what's covered. It also names what it returns (USD market price + 30-day change, sorted most expensive first), which separates it cleanly from card_price and set_prices.

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?

Explicit trigger: 'use this when the user asks about sealed product prices in one game,' plus an explicit alternative for the contrasting case ('for one named product, search_cards plus card_price is more direct'). The routing decision is fully resolved without opening a schema.

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