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

Beyond the readOnly/openWorld annotations, it discloses that history begins at tracking_since with nothing observed earlier, that free access covers only the last 30 days (pointing at history_window), that statuses are relayed 'as published' with the English labels being the service's own translation, and that it is relay-only. These are exactly the caveats an agent cannot get from annotations.

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?

Front-loads the core question and is compact, but the stacked parentheticals ('as published, with English labels as our translation') and the terse 'Relay only' fragment make the back half dense. Nothing is wasted, though a touch more structure would help.

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?

An output schema exists so return values need not be re-explained; the description instead covers the things the schema and annotations cannot: history start bound, free-tier window, translation provenance and the relay nature. An agent has everything needed to call and interpret this correctly.

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%, so the schema already documents since, limit, yj_code and change_type with formats and enum values. The description names the returned change fields (YJ code, product, before/after status, versions compared) but adds no filter syntax or semantics beyond what the schema provides, so baseline 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 precise verb and resource: which products in the Japan MHLW supply status list changed status, or were added/removed/modified, since a date. The parenthetical 'MHLW publishes only the current list' immediately distinguishes it from the sibling drug_supply_status (current-state) tool.

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?

Explains the context that makes this tool necessary (the publisher keeps only the current list, so historical diffs come from this service's own version record) and flags the free window of 30 days. It does not explicitly name drug_supply_status as the alternative for current-state queries, so it stops short of full when/when-not routing.

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