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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered; the description adds genuine value beyond them by disclosing what results contain (market price plus marketplace price) and the conditional effect of deliveryCountry on availability. It stops short of covering pagination (cursor) or result-size behavior, which keeps it below 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?

Two sentences, front-loaded with the core action and searchable keys, followed by the result-content sentence. Efficient, with no filler; only minor loss for packing several concepts into a single long second sentence.

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 19-parameter tool with a nested filters object and no output schema, the description covers the search surface and the key result fields adequately. It leaves out pagination/cursor behavior, limit semantics, and how marketplace filters combine with game/cardNames, which an agent must infer from the schema alone.

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 79%, so the schema carries most parameter meaning and the baseline of 3 applies. The description groups the searchable fields but adds no syntax or format guidance for cursor, limit, finish, sortBy/sortDirection, or the nested filters object beyond what the schema already documents.

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 verb (searches) and a specific resource (CardNexus cards and sealed products), then enumerates the searchable keys (name, set code, print number, game, type, attributes). An agent can distinguish this from get_products or search_listings by the fact that it spans both cards and sealed product in one query, though no sibling is named explicitly.

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 by the catalog-search framing and the note that supplying a delivery country yields the cheapest shipping copy, which hints at the buy-side use case. However, there is no explicit statement of when to prefer this over search_inventory or search_listings, and no exclusions or prerequisites are given.

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