90年代日本語サイトのホスト辞書

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

With no annotations, the description carries the transparency burden. It states '返す' (returns), implying a read-only operation, but does not explicitly mention side effects, authentication, or whether it performs network calls. For a simple lookup tool, this is adequate but not rich.

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 two sentences with zero waste. It front-loads the core purpose, gives concrete examples, and then states use cases. Every clause earns its place.

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 one optional enum parameter, no output schema, and no annotations, the description is sufficiently complete. It explains what the tool returns and how to use it. No critical gaps remain for an agent to select and invoke it 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?

Schema coverage is 100%, so the baseline is 3. The description does not mention the 'category' parameter at all, but the schema's own description already explains it well ('種別で絞る。community は発見の入口'). Description adds no extra parameter-level meaning.

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 states a specific verb+resource: '一覧を返す' (returns a list) of legacy hosting services. It provides concrete examples (Geocities, @nifty, BIGLOBE) that distinguish it from sibling search/wayback tools, making its purpose immediately clear.

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 explicit use cases: 'CDX 探索の起点選びや site: 絞り込みに使う' (used for choosing starting points for CDX exploration and site: filtering). This provides clear context but does not explicitly mention alternatives or when not to use it, so it stops short of a 5.

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