Get Pokémon cards by id

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, but the description goes far beyond that. It discloses that missing ids are omitted, provides detailed data coverage statistics (attacks on 33% of catalogue, etc.), explains that null fields mean 'we do not hold it' rather than absence of the attribute, and explicitly states that legalities cannot be answered. This is exemplary transparency beyond the structured annotations.

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?

The description is longer than typical but every sentence carries weight. It is front-loaded with the purpose and id format, then logically proceeds to missing-id behavior, data coverage, null semantics, and limitations. There is no fluff, though the statistical details could be condensed for brevity. It is well-structured and readable.

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?

With no output schema, the description bears the full burden of setting expectations. It covers id format, missing-id handling, field coverage, null semantics, and explicitly states what the API cannot answer (legalities). It even advises the agent to say so rather than infer. This is comprehensive for a tool of this complexity, leaving no critical caveat unaddressed.

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?

The schema already documents ids (with a description) and include_prices (with a description), but lang has no description beyond its enum. The description significantly enriches the ids parameter by explaining the exact format and legacy id resolution, which is critical for correct invocation. It adds no info for lang or include_prices, but those are self-evident from the schema. Given the schema coverage of 67%, the description compensates well for the required parameter.

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?

The description clearly states the verb ('Fetch'), the resource ('cards by id'), and the single-call batching capability. It distinguishes itself from the sibling search tool by being id-based, and even specifies the exact id format (set code-dash-collector number, e.g. 'bs-4') with a legacy alias example, leaving no ambiguity about what this tool does.

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 description makes it clear that ids are required, which implies that this tool is for id-based lookup rather than search. It also notes that missing ids are silently omitted, guiding the agent to compare requested vs. found. However, it does not explicitly mention alternatives like ptcg_search_cards for when ids are not available, so it lacks an explicit exclusion clause.

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