和暦⇔西暦変換

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

Annotations already declare readOnlyHint=true, so the safety is established. The description adds behavioral context: the conversion direction depends on which parameters are provided, and era names support Romanized forms. It doesn't cover edge cases like conflicting parameters, but the core behavior is disclosed.

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 concise and well-structured: two sentences cover purpose, usage directions, an example, and romanization support. Every sentence carries relevant information without waste.

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 simple converter with a read-only annotation and full schema coverage, the description is mostly complete. It gives a concrete output example for era→westward, but doesn't explicitly describe the return format for date→era. Still, the conversion concept is clear and the example implies the output form.

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 input schema already provides 100% parameter descriptions, so the baseline is 3. The tool description adds value by showing how parameters combine (e.g., era='令和', eraYear=6 → 2024) and clarifying that date is for one direction while era/eraYear are for the other, which is beyond individual schema entries.

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 that the tool performs bidirectional conversion between Japanese era (和暦) and Western calendar (西暦). It provides specific usage for both directions and distinguishes itself from sibling tools that handle holidays and date info, not era conversion.

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 explicitly tells which parameters to specify for each conversion direction (w→e: date; e→w: era and eraYear) and includes a concrete example. It doesn't mention when not to use or alternatives, but the tool's unique purpose is obvious.

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