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

With no annotations, the description carries the full burden of behavioral disclosure. It does reveal the sorting criterion and the slug's genre-filtering role, but it does not mention return shape, empty results, error behavior, or whether the data source is live. This is adequate but not deeply transparent.

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 compact and front-loaded: it states the tool's purpose first, then defines the one required parameter, and finishes with a pointer to the index sibling. Every clause earns its place and there is no redundant filler.

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 simple lookup tool with one required slug parameter, the description covers the core call: what is returned, the sort ordering, the parameter's meaning, and where to get the full list. It is slightly incomplete in not clarifying the exact columns or units implied by '量', but it is still nearly sufficient for an agent to call the tool correctly.

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 provides only a bare 'slug' string with no description, so the description's explanation that the slug is the genre in English letters such as hotate, unagi, and kani adds substantial semantic value. It compensates well for the 0% schema coverage, though it does not provide an exhaustive list of valid genre slugs.

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 output: a comparison table of furusato tax return gifts, sorted by amount per 10,000 yen donation. It also specifies the role of the slug (genre in roman letters) and distinguishes itself from furusato_index by pointing there for the list.

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 gives clear context for use: provide a genre slug like hotate or unagi to get the sorted comparison table. It also routes list-style requests to furusato_index, providing a useful alternative, though it does not explicitly discuss when to choose this over the other furusato siblings.

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