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 'Markdown output' and 'ranking' context, but does not mention the json/xlsx export options or that xlsx returns a base64 field; those are only in the schema. No contradiction with annotations.

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 a single clear sentence (plus a Japanese translation) that front-loads the purpose, scope, and metric list. There is no filler, though the redundancy of listing metrics twice adds a little length.

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?

With 7 parameters and no output schema, the description is under-specified. It does not explain the response structure, the xlsx base64 behavior, or how neighborhood/propertyType affect the comparison. An agent would have to rely on the schema alone, which is incomplete at 57% coverage, to call this 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?

Schema coverage is 57% (above 50%), so baseline is 3. The description maps metrics to land price, population, risk, and investment, which partially explains the 'metrics' parameter, but it does not add clarity for propertyType, includeMarkdown, or neighborhood. The 'Markdown output' claim conflicts with the default exportFormat of 'json' in the schema, a minor semantic inconsistency.

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 ('Compare') and resource ('prefectures'), with a concrete scope ('up to 5') and a list of metrics (land price, population, risk, investment score). This clearly differentiates it from sibling tools like composite_value_score or cross_analyze_real_estate_market, which target different analyses.

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 implies usage when comparing prefectures across the listed metrics, but does not explicitly mention when not to use it or point to alternatives. There is no exclusions or routing guidance, making it adequate but not strong.

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