weather_areas

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and open-world behavior are covered. The description adds useful context about the relationship to weather tools and the nature of the data (valid codes and names), which complements the annotations without contradicting them.

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?

The description is a single, front-loaded sentence that conveys the tool's purpose and scope with no filler. Every word earns its place, and it is appropriately concise for such a simple tool.

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 the tool's simplicity, the lack of parameters, and the presence of annotations, the description fully covers what the agent needs to know: it lists JMA region codes and names that are valid for weather tools. No output schema is needed because the description states the output contents clearly.

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 has zero parameters with an empty input schema, so there is no parameter documentation burden. Per the baseline for zero-parameter tools, a score of 4 is appropriate because there is nothing to explain beyond what the schema already shows.

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 the tool's function: listing valid JMA region codes and names used by weather tools. It uses a specific verb ('List') and a concrete resource, and it distinguishes itself from sibling weather tools by being the reference for accepted region identifiers.

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 implies when to use this tool: before calling weather tools that require JMA region codes. It clearly says the codes are 'accepted by the weather tools,' giving enough context without needing explicit when-not-to-use guidance for such a simple reference tool.

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