Get Rakuten Travel Area Classification

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

Annotations already mark it as readOnly, idempotent, and openWorld. The description adds the hierarchy structure, which is consistent and provides additional context without contradiction.

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 in English (with Japanese translation) that front-load the purpose and include a usage note. No unnecessary words.

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?

Given zero parameters and rich annotations, the description covers the essential behavior. However, the lack of an output schema means the agent may not know the exact response format, but the description hints at the code field names.

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?

No parameters exist, so the description cannot add meaning to them. However, it explains the output codes' structure, which compensates for the absence of an output schema. Baseline for 0 params is 4.

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 clearly states 'Get the full Rakuten Travel area-code hierarchy' and explains the hierarchy levels (Japan→prefecture→city→district). It distinguishes itself from sibling hotel search tools by being the source of location codes.

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?

Explicitly instructs to use the returned codes as parameters in hotel search tools. While it doesn't mention when not to use it, the context makes it clear as a preliminary step.

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