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

The description adds significant context beyond the readOnlyHint annotation by explaining the distinction between '決定' and '報道' amounts, clarifying that both are decided amounts with different announcement dates, and specifying the unit (60kg per yen). This helps the agent avoid misinterpretation.

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 detailed but well-structured, front-loading the core purpose and then explaining nuances. It includes necessary disclaimers about data interpretation without excessive repetition. It could be slightly more concise but is efficient enough.

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 no output schema, the description explains what the tool returns: amounts per JA/prefecture, comparison with previous year, announcement dates, and unannounced flags. It also mentions the data source and unit. This covers the key aspects for a complex domain, though pagination or error handling is not mentioned.

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 description coverage is 100% for all three parameters (brand, prefecture, onlyAnnounced), each with clear descriptions. The tool description adds no additional parameter semantics beyond what the schema already provides, so baseline 3 applies.

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 advance payment amounts for 2026 rice crop per JA and prefecture, with specific verb '返す' and resource '概算金（仮渡金）の提示額'. It also mentions comparison, announcement dates, and unannounced status. This is distinct from sibling tools which deal with subsidies and articles.

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 by stating that agri-ja.net is a unique aggregation source and that few other cross-sectional lists exist, implying this tool is the go-to for such queries. It also gives guidance on interpreting the two categories of announcements, though it does not explicitly exclude alternatives.

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