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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real behavioral content beyond that: the compared facets and the item-count bounds. It does not describe the response shape, which matters here because there is no output 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?

Two tight sentences that front-load the trigger before the mechanics, with no filler. The bilingual phrasing and embedded example earn their space by disambiguating intent.

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 carries the return-value burden, and it does so partially by listing the facets being compared. The unaddressed 'lang' parameter and the absent description of the report's shape are the remaining gaps for a 2-parameter read tool.

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%: 'ids' is already documented with an example and minItems/maxItems, and the description only restates the 2–8 range. The 'lang' parameter is unexplained in both the schema description and the description, leaving a real gap about whether it localizes labels or the whole report.

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 and resource ('Compare 2–8 equipment items') and enumerates the compared dimensions (raw parameter blocks, effects, price, type, source count). This is distinguishable from all siblings, which are find/lookup/search tools, though the description never says so 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?

Gives an explicit trigger condition and a concrete example ('轮回之翼和グレートボウ有什么区别'), so an agent knows exactly when to reach for this tool. It does not name alternatives or state when not to use it (for example, single-item lookups, which should go to get_entity).

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