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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description adds meaningful behavioral context: returned fields (peak window start–end, confidence in days, nearest rail station, leaf type, page URL) and sort order (prominence then proximity). This goes beyond the annotations without contradicting them.

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 dense but every sentence earns its place: core behavior, question types, parameter guidance, return format, examples. Key scoping information is front-loaded, and examples at the end reinforce the rules without adding fluff.

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 11 parameters, no required fields, no output schema, and three sibling tools, the description still covers the essential call patterns, parameter combinations, return payload, and sorting behavior. The example prompts and example call give an agent enough to select and invoke this tool correctly in varied user scenarios.

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 100%, but the description adds relational meaning: date OR date_from/date_to, near OR lat/lon, radius_km as an optional modifier, and region/prefecture as restrictors. The example call {date: '2026-11-20', near: 'Kyoto', radius_km: 60} demonstrates valid parameter combination, which the flat schema alone does not convey.

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: 'Find Japan autumn-foliage viewing spots' whose forecast window covers a date/range. The three listed question types ('where should I go on <date>?', 'when does <place> peak?', 'is <spot> still at peak on <date>?') make the tool's specialized purpose unmistakable and distinguish it from generic siblings like search or fetch.

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 says 'Use it for...' and provides concrete example prompts and an example call, giving clear context on when to invoke the tool. It does not explicitly state when not to use it or name alternatives, so it stops short of a 5.

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