get_stats_fields

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. The description only states what the tool returns, without mentioning any behavioral traits such as whether this is a read-only operation, potential rate limits, authentication requirements, or what format the output takes. While the existence of an output schema helps, the description itself lacks behavioral context.

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 extremely concise - a single Japanese sentence that directly states the tool's purpose with no wasted words. It's appropriately sized for a simple retrieval tool with no parameters and gets straight to the point without unnecessary elaboration.

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 that this is a simple retrieval tool with zero parameters and an output schema exists, the description is reasonably complete for its purpose. The output schema will handle documenting return values, so the description only needs to state what the tool does. However, it could benefit from clarifying how this differs from similar sibling tools in the context of the overall API.

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, and schema description coverage is 100% (though there are no parameters to describe). The description doesn't need to compensate for any parameter documentation gaps. A baseline of 4 is appropriate for a parameterless tool where the schema fully covers the input structure (which is empty).

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 purpose: '統計分野コード一覧を返す' (returns a list of statistical field codes). It uses a specific verb ('返す' - returns) and resource ('統計分野コード一覧' - statistical field code list). However, it doesn't explicitly differentiate from sibling tools like 'get_stats_list' or 'get_meta_info', which might also return lists of statistical information.

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 no guidance on when to use this tool versus alternatives. With multiple sibling tools that appear to retrieve statistical data (e.g., 'get_stats_list', 'get_meta_info', 'get_stats_data'), there's no indication of what distinguishes this tool's functionality or when it should be preferred over other list-retrieval tools.

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