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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds that the result is a canonical list of keys with Japanese and English names, plus procedures and measures — useful context, though the output schema already carries the return shape.

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?

Two sentences: the first scopes what the tables cover, the second states what is returned. Front-loaded, no filler, and the key/name detail lands before the return summary.

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 zero parameters and an output schema present, the description needn't spell out return values or input semantics. It gives enough context (ISA processing tables, canonical keys, bilingual names) for an agent to know what this enumeration yields.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The mention of accepted keys/names refers to returned values, not inputs.

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 — the statuses of residence and procedures covered by ISA's processing-time tables — plus the canonical keys/names the service accepts. That is a clear verb-free but concrete lookup purpose. It does not distinguish itself from siblings such as residence_processing_history or residence_processing_latest, which is the only thing keeping it from a 5.

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 is only implied: asking 'which keys and names does this service accept' hints that this is a discovery/enumeration call to run before querying history or latest. There is no explicit when-to-use, when-not-to-use, or named alternative.

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