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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint. The description adds context about the data source (GSI) and geographic scope, but does not reveal additional behavioral traits beyond what annotations imply. No contradictions.

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 very concise, using two sentences to convey purpose, source, and a usage guideline. It is front-loaded with English followed by Japanese, and every sentence adds value. No unnecessary words.

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 the presence of an output schema and annotations, the description sufficiently covers the tool's purpose, source API, and a key usage instruction. It does not mention rate limits or error conditions, but the openWorldHint and idempotentHint mitigate some concerns.

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 descriptions already cover 100% of parameters with Japanese text about latitude/longitude ranges. The description adds English bilingual context but does not provide new semantic meaning beyond the schema. Baseline 3 is appropriate.

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 clearly states the tool reverse geocodes latitude/longitude to municipality code and town name using the GSI API, specifying geographic focus on Japan. It distinguishes itself from sibling tools by including 'Torify namespace' and providing bilingual text, but not explicitly differentiating from the generic reverseGeocode sibling. However, the purpose is very specific and 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 explicitly instructs to use for mapping real coordinates to an official municipality and warns against inferring from memory. While it does not list when not to use or compare with siblings, the guidance is clear and actionable for an AI agent.

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