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

Annotations only declare readOnlyHint and openWorldHint; the description adds real behavioral context beyond them: the status vocabulary (normal, limited shipment sub-categories, supply suspended), that English labels are the service's own translation, that a previously-observed status is included, and a relay-only/not-medical-advice caveat.

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-loaded as a direct question, followed by lookup keys, return contents, and a short disclaimer; roughly three compact sentences with little waste, though the return-value enumeration is somewhat list-heavy.

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?

For a read-only open-world lookup with a full input schema, complete parameter docs, and an output schema, the description covers what the agent needs: what is queried, what comes back, and the data caveats. Only the sibling differentiation (drug_supply_changes) is missing.

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 both parameters are documented there, including formats and the max_results range. The description repeats the lookup keys but adds no format or constraint 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 states a specific verb (look up) and resource (MHLW-published shipment status for a Japanese prescription drug) and enumerates the accepted lookup keys (YJ code, NHI price list code, product/ingredient name). It does not explicitly contrast itself with the sibling drug_supply_changes, though the mention of 'previous status observed by this service' hints at the distinction.

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 tells the agent how to query (which identifier formats are accepted) but never states when to pick this tool over drug_supply_changes or catalog, nor any exclusions. Usage is implied by the resource, not spelled out.

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