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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is externally provided. The description adds useful context about what Yomitas is and how site registration works, but it does not disclose output format, rate limits, or other operational details. For a zero-parameter read-only tool this is acceptable, though 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 core function is front-loaded in the first sentence. The following sentences give helpful background about the service and a use case, though the site-owner registration detail is tangential to invoking the tool. Overall compact and readable.

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 zero parameters and existing read-only annotations, the description covers purpose and usage sufficiently. Since there is no output schema, a more specific description of what the overview contains would close the only real gap, but for a simple info tool this is likely enough.

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 100% schema coverage (empty schema). The description correctly avoids inventing parameter details, so the baseline of 4 for parameter-free tools applies.

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 opens with a specific verb and resource: '「ヨミタス」の概要を返します' (returns the overview of Yomitas). This clearly distinguishes the tool from siblings like get_page or list_pages, which target individual pages or lists.

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 final sentence 'どんなサービスかを最初に知りたいときに使います' gives an explicit use case: use when first learning about the service. However, it does not name alternatives or state when not to use it, so it misses a bit of full comparative guidance.

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