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.

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

Annotations already declare this as a read-only operation (readOnlyHint=true). The description adds valuable behavioral context by stating that omitting the date returns today's information in Japan time, which is not evident from the schema or annotations. It does not mention error handling or the exact return format, but these are minor for a read-only tool.

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 two sentences, front-loaded with the core purpose, and contains no redundant or unrelated information. Every word earns its place.

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 single-parameter read-only tool, the description enumerates the three return components (weekday, holiday flag, era notation) and the default behavior. No output schema exists, so the description shoulders the burden of explaining return values, which it does sufficiently. Minor caveat: it does not specify the exact response structure or how 'holiday' is determined, but this is acceptable for a simple tool.

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 schema documents the date parameter with format and example. The description adds the key semantic that the parameter is optional and defaults to today (Japan time), which is not present in the schema. This goes beyond the baseline.

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 returns the weekday (in Japanese), whether the date is a holiday, and the Japanese era notation for a given date. This specific verb+resource combination distinguishes it from sibling tools like jp_list_holidays (list holidays) and jp_convert_era (convert eras).

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 usage for retrieving detailed information about a single date, but it does not explicitly mention when to use this tool over the sibling alternatives or provide any exclusions. Since there are sibling tools, the lack of explicit differentiation is a gap.

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

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

Annotations already declare readOnlyHint=true, and the description adds that the list includes substitute holidays and national holidays, plus the supported year range. This goes beyond the annotation by specifying scope and inclusion criteria, which helps the agent understand exactly what will be returned.

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 two short, front-loaded sentences with no redundancy. It efficiently conveys the main action, additional inclusions, and the valid range.

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 read-only holiday list tool, the description fully covers the input scope, output, and constraints. The annotations handle safety, and the schema covers parameters, so no further context is needed.

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 coverage is 100% with clear descriptions for both year and month, so the description adds little beyond what the schema already provides. It does reinforce that month is optional via 'or year/month', which is already evident from the schema's required field list.

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 'returns a list of Japanese holidays for the specified year (or year/month)', using a specific verb and resource. It distinguishes itself from siblings like jp_next_holiday by focusing on listing holidays for a given period rather than finding the next holiday.

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 provides clear context on what the tool does and its supported range (2020-2099), making the use case obvious for holiday list retrieval. However, it does not explicitly mention alternatives or when not to use it, such as pointing to jp_next_holiday for single-next-holiday queries.

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

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

Annotations already declare readOnlyHint=true and openWorldHint=false, covering the safety and scope profile. The description adds useful behavioral context: the timezone for the default date (Japan time) and the output contents (holiday date and days remaining). This aligns with the annotations and adds value beyond 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 efficiently conveys the essential behavior: the operation, the input, the default, and the output. Every word earns its place, with no redundancy or filler.

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 read-only tool with one optional parameter and no output schema, the description fully explains the return value and input semantics. It does not need to describe return formatting or error handling given the straightforward nature, and the annotations already cover the safety profile.

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 fully describes the 'from' parameter (start date, default today), so the baseline is 3. The tool description enhances this by specifying '日本時間' (Japan time) for the default, adding a meaningful detail not present in the schema description. Thus, it goes slightly beyond the schema.

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 returns the nearest holiday on or after a specified date (default today) and the number of days remaining. This is a specific verb+resource combination that distinguishes it from sibling tools like jp_list_holidays (which lists holidays) and jp_date_info (which provides date details).

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 provides clear context: use it to find the next holiday from a starting date, with today (Japan time) as the default. However, it does not explicitly mention when not to use it or compare against alternatives such as jp_list_holidays, so it stops short of the highest bar.

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