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

Annotations already declare a safe read-only, non-destructive, closed-world operation, so the safety burden is covered. With no output schema, the description usefully discloses the return contents (type, intro, page count, main pages), which is real added value, though nothing is said about caching, freshness, or limits.

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 short sentences, front-loaded with what is returned before the usage hint. The opening sentence embeds a long, oddly specific restaurant name/domain, which adds bulk without helping an agent decide or call; otherwise efficient.

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 parameterless read-only tool with no output schema, the description does the essential work of enumerating the returned fields and stating when to call it. Auth, quota, and failure behavior go unmentioned, but little is genuinely missing for correct invocation.

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 takes zero parameters and the schema is trivially covered, so the baseline is 4. The description appropriately adds no parameter detail because there is nothing to document.

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 names a specific verb and resource: it returns what a site is, listing what's available (種類・紹介文・読み込んだページ数・主なページ). This is clearly a site-level summary distinct from the page-level siblings (get_page, list_pages, fetch), though it never names a sibling to make the boundary explicit.

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?

"最初にサイトの全体像をつかみたいときに使います" gives an explicit when-to-use condition (first, to grasp the overall picture). However, it names no alternative tool or when-not condition, leaving sibling routing to inference.

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