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

Annotations already establish the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description is free to add value elsewhere — and it does, disclosing that each call costs 1 credit and requires a Growth-or-higher access tier. These are operationally important facts absent from the structured fields. It omits behavior on an invalid or missing card_id, 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?

One dense sentence with the resource and return fields front-loaded and zero filler. The telegraphic style leaves "Growth and up" and "1 credit" slightly under-explained, which is the only structural cost.

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 one-parameter read tool with full annotation coverage, the definition is nearly complete: it enumerates what comes back, which substitutes for the absent output schema, and states cost and access tier. Missing only failure behavior and an explicit pointer to the search/batch siblings for related needs.

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% and the single card_id parameter is documented in-schema as "Valo.Data card id" with bounds, so the description need not repeat it. The description adds no meaning beyond the schema for the parameter — 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?

"Full sheet of one card" gives a specific verb (retrieve the full record) and resource, and the field list (edition, number, rarity, images, marketplace ids) makes the payload concrete. It does not name the sibling it should be preferred over (e.g. get_card_prices for pricing, search_cards for discovery), so differentiation is left implicit.

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 only implied: an agent infers this is the tool to call once it already holds a card_id and wants the complete record rather than prices or search results. There is no explicit when-to-use/when-not statement and no routing to siblings like get_cards_batch or identify_card, though the "1 credit" and "Growth and up" notes do give a cost/entitlement signal that informs the decision.

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