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 covered. The description adds useful behavioral context: it is limited to 10 prefectures and supports branding via parameters like companyName/agentName. However, it does not disclose return format details (e.g., that PDF returns a base64 field) beyond what the schema mentions, nor any other behavioral traits.

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 concise—two short sentences in English and their Japanese translation. The core purpose is front-loaded. The bilingual duplication adds length but the content is minimal and not verbose; it sacrifices some compactness for clarity, which is acceptable.

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 tool with 13 parameters and no output schema, the description is too sparse. It does not explain what 'comprehensive' includes, what the purpose options mean, or how this differs from similar report tools. The scope limitation to 10 prefectures is noted, but the description lacks the depth needed for an agent to decide when this tool is appropriate and what to expect beyond the schema.

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 description coverage is 77%, so the baseline is 3. The description adds a small amount of parameter context (branding support, 10 prefectures) but does not explain the required 'area' and 'purpose' parameters beyond what the schema provides. Since most parameters have inline descriptions, the description's contribution is marginal, keeping the score at the baseline.

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 clear verb and resource: 'Generate comprehensive area report in Markdown/PDF with branding support.' It immediately indicates the output formats and branding capability. The mention of '10 prefectures' scopes the resource, and while it doesn't name a sibling, the purpose is distinct enough from analysis tools like 'compare_prefectures' or 'quick_visual_summary' to be 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?

The description gives no guidance on when to use this tool versus alternatives. It does not mention any sibling tools, nor does it state prerequisites or conditions for selection. The reader is left to infer that this is the tool for generating reports, but no explicit usage context is provided.

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