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

The annotations already mark this as read-only and open-world, and the description adds real context beyond them: the data is this service's own page-version record (MHLW keeps none), each change carries before/after plus the service's first-read time, and history is capped at a free 30-day window. It stops short of explaining what happens outside that window or whether pagination via limit truncates results.

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?

Three dense sentences, front-loaded with the core question and followed by provenance, result shape, filters, and the window limit. The parenthetical about MHLW keeping no record is slightly awkward but still earns its place by establishing data provenance.

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 an output schema present, the description doesn't need to spell out return values, yet it still sketches the before/after and first-read-time fields. Provenance, filtering, and the 30-day cap are all covered; only edge behavior at the window boundary or for unmatched exam values is left unstated.

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 100%, with each parameter, the enum values, and the ISO 8601 format documented in the schema. The description only restates that exam and change_type are optional filters, adding no meaning beyond the schema, so the baseline of 3 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?

States a specific verb-and-resource: which exam dates on MHLW's national qualification exam list changed, appeared, or left it, since a given date. That is clearly distinct from the sibling exam_schedule_lookup, which presumably returns current state rather than a diff.

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?

Usage context is implied rather than stated: the tool diffs page versions over time, and 'Free window: last 30 days' signals a limit, but the description never says when to prefer this over exam_schedule_lookup or what to do for changes older than 30 days.

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