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

Beyond readOnlyHint/openWorldHint, it discloses data provenance ('this service's own record of list versions; MEXT keeps none'), date attribution ('MEXT's dates, still listed by MEXT'), and a tier/access limit ('Free window: last 30 days') — exactly the kind of context annotations cannot carry. The 'free window' phrasing is slightly ambiguous about whether it caps query range or access tier.

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?

It is front-loaded with the core question and contains no filler, but it is a single ~60-word sentence with multiple nested parentheticals that is hard to scan. Splitting the two result families and the access limit into separate sentences would help without adding 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?

Output schema covers return values and annotations cover the safety profile, and the description still supplies provenance, date semantics, the free window, and the 'facts not assessment' boundary. It does not explain whether the two result families are merged, ordered, or paged by the limit parameter.

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%, so the baseline is 3; the description earns above that by clarifying that 'since' is interpreted differently for the two result families — this service's own list-version records versus MEXT's publication dates. That dual date basis is genuinely non-obvious and not derivable from the schema alone.

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 resource and verb: which schools were added/changed/removed/reappeared on MEXT's tuition-support eligibility list since a date, plus which revocation and noncompliance publications appeared. Its change-log framing implicitly separates it from the sibling tuition_support_school_lookup (current-state lookup), though no sibling is named outright.

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?

'since a date' establishes the temporal-scoping precondition, 'Free window: last 30 days' tells the agent how far back queries are viable, and 'Published facts only, not an assessment' is an explicit scope boundary telling the agent not to use it for evaluation. No named alternative or explicit when-not case, keeping it below 5.

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