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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only states 'Browser-based tool', but does not disclose whether it opens a UI, returns data, requires internet, or how results are presented. This is sparse for an unannotated tool.

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 concise sentence that names the specific carriers and includes the essential browser-based qualifier. There is no filler or redundant information.

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 zero-parameter browser-based tool, the description is mostly complete: it identifies the carriers and purpose. Minor gaps include no mention of output format or whether it opens a webpage, but the low complexity and schema make it acceptable.

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 tool has zero parameters and the schema coverage is complete, so the description does not need to document parameter details. Baseline 4 for a no-parameter tool is appropriate.

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?

Clearly states a specific action (compare rates) and resource (Yamato, Yu-Pack, Sagawa). The named carriers distinguish it from the sibling tool mercari-shipping-compare, making its purpose unambiguous.

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?

Implies use when comparing rates among these three carriers, but provides no explicit when-to-use or when-not-to-use guidance, nor mentions alternatives. The parenthetical 'Browser-based tool' hints at modality but does not clarify when to prefer this over sibling calculators.

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