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

Annotations already declare readOnly, idempotent, non-open-world, so the description is free to focus on what annotations cannot express: the 25-match result cap, the exact fields returned, the USD price currency, and the six-game coverage boundary. That is meaningful added context beyond the structured hints.

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, front-loaded with the trigger and the reason an agent would call it, then result shape, then coverage limits. No filler, though the return-field enumeration is slightly verbose given an output schema exists.

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?

For a read-only search with full schema coverage and an output schema, the description supplies everything essential: trigger, purpose of results, result cap, currency, and supported games. The only gap is guidance on when its sibling `search` is the better choice.

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%, so query/game/limit are already well documented, and the enum values and 1–25 range appear in the schema rather than the description. The description only indirectly reinforces the limit ('up to 25 matches') and adds no syntax guidance beyond the schema's own example. 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?

Specific verb+resource ('search_cards' for a card/product lookup) plus the explicit motivation — obtaining product_id or group_id for downstream calls. It also states scope (the six supported games) and output shape, which lets an agent distinguish it from card_price, set_prices, or search without opening any schema.

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?

The opening clause gives a concrete trigger ('when the user names a trading card or sealed product') and names the downstream tools that consume its output, which is a genuine routing signal. It does not, however, say when to prefer the sibling `search` or `fetch` instead, leaving one comparison implicit.

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