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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description goes further by disclosing data-freshness caveats (possibly_stale, retrieved_at, source) and the before/after revision structure. It also sets an explicit scope boundary on application periods and advises confirming on the official page, which tells the agent the data may be incomplete.

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?

Dense but front-loaded: the core question, the input form, the return shape, the scope exclusion, and the caveat are each one clause with no filler. Nothing could be removed without losing an agent-relevant fact.

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 need not enumerate return fields, yet it still sketches next_events, revisions, and freshness flags, and it covers both the single-exam and listing modes. The only real hole is the absence of routing against the sibling change-tracking tool.

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% and every parameter is documented in the schema, including exam_id examples and category meanings. The description restates the exam/omit-to-list/category behavior but adds no new syntax or format detail 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?

The description names a specific verb and resource (exam dates and result-announcement dates for Japanese national exams, from MHLW's list page) and gives concrete exam_id examples. It is clearly a lookup tool, though the 'did the dates change?' clause overlaps with the sibling exam_schedule_changes, which it never names.

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?

It explains the calling pattern ('give exam ... omit it to list exams, optionally by category') and one exclusion ('Application periods are not covered'), which is genuinely useful. But it never says when to use it versus exam_schedule_changes, which covers the revision angle this tool also returns, so the choice is left to inference.

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