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

Annotations already establish readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely useful semantics beyond that: it enumerates the outcome states and critically warns that no_match_in_checked_list 'does not mean not organic' and that no_longer_listed reasons may be unpublished or inferred, plus an authoritative-source caveat. These interpretive notes go well past the structured fields.

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?

Three sentences, front-loaded with the core question, then the lookup keys, then the return semantics and caveat. Dense and mostly waste-free, though the enumerated status list is slightly long given an output schema exists. Every sentence still carries decision-relevant information.

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 read-only, open-world lookup with a 100%-covered schema and an existing output schema, this is complete: purpose, accepted filter dimensions, return-state interpretation, and an authoritative-source warning are all present. An agent has everything needed to call it and interpret results correctly.

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%, so the schema already documents every parameter's format, codes, and constraints. The description restates the filter dimensions (cert number, name with 2+ char/organization-only rule, country, prefecture, category, certifier) but adds no syntax or format detail beyond what the schema provides. 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?

States a specific verb (look up) and resource (Japan's official MAFF list of organic JAS certified operators), plus scope (domestic or foreign). An agent immediately understands this is a membership/verification lookup against a government registry, distinct from a changes feed like organic_jas_changes. Framing it as a yes/no question makes the intent unmistakable.

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 'Is this operator...?' framing implies the verification use case, and the closing 'Confirm with the certification body' caveat signals this is not the authoritative source. However, it never states when to reach for this versus a sibling like organic_jas_changes, nor any exclusions. Usage is implied rather than explicit.

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