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

The annotations already declare readOnlyHint=true, and the description meaningfully extends this by specifying exactly what checks are performed and what advice will be returned. The clarification that it takes gameplay card ids, not printing ids, adds important operational context beyond the schema.

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 a single dense sentence, front-loaded with the core purpose, followed by a compact list of validation rules and output topics. Every phrase earns its place; there is no filler or repetition of the title.

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?

Given there is no output schema, the description does well to enumerate the validation rules and the categories of advice the caller can expect. It could additionally mention how locale affects output or what happens for invalid decks, but the essential information for selecting and invoking the tool is present.

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 coverage is 100%, so the schema fully documents cards and locale. The description adds valuable disambiguation by emphasizing that gameplay card ids are required, not printing ids, which is a subtle but critical detail for correct invocation.

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 names a specific verb ('Check'), a specific resource ('a 20-card Pokémon TCG Pocket deck'), and precisely enumerates the validation rules and advice categories. This makes the tool's purpose unmistakable and clearly distinct from siblings like suggest_deck or simulate_matchup.

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 intended use case—evaluating an existing decklist against game rules—is clearly implied by the description, but it does not explicitly state when to use this tool versus alternatives such as suggest_deck or simulate_matchup. There is no 'use this when...' or 'instead of...' guidance.

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