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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile is fully covered by structured data. The description adds real value on currency behavior and the changePct sign/scale convention, but says nothing about ordering, ties, or what an empty market returns.

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 tight sentences, front-loaded with the core purpose and followed by the currency and changePct semantics. No filler; each sentence carries distinct information, though the changePct sentence could be merged into the parameter layering more cleanly.

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 list tool with no output schema, 4 optional params, and full annotation coverage, the description supplies the missing semantics (currency, changePct units, window/by behavior). It is nearly complete, with only return-shape/pagination left unaddressed, which is acceptable for a bounded 1-10 item result.

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 50%, and the description compensates meaningfully: it defines changePct as a percentage (12.5 = +12.5%), states the currency behavior when source is omitted, and pins the unit interpretation to get_card's convention. This clarifies 'by' (pct vs abs) and 'source' beyond the schema's own enum text.

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 resource and scope: biggest gainers/losers across the Gundam market over a 7-day or monthly window, sorted by pct or absolute change. An agent can immediately tell what it returns. However, it never names the similar siblings (price_list, best_buys) it should be chosen over, so differentiation is only implied by scope.

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?

No explicit when-to-use, when-not-to-use, or alternative naming is present. The reader must infer from the name and scope that this is for market-trend queries rather than per-card pricing (price_list) or curated deals (best_buys). Cross-referencing get_card only explains a formatting convention, not selection.

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