Reference data

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds only that these lists support correct document filling; it does not say whether results are cached/static, how large the lists are, or what each entry contains. With annotations carrying the main burden, this is adequate but thin.

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?

One compact sentence with the verb front-loaded and the four kinds listed efficiently. Only 'needed to fill documents correctly' is slightly vague filler, but it does carry the usage hint, so almost 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 simple one-enum lookup tool with no output schema, the definition covers what is fetched but not what comes back (field shapes per kind), which matters because there is no output schema to fall back on. Adequate to invoke, incomplete for interpreting results.

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 0%, but the single parameter is an enum whose four values are self-describing and are restated in the description. The description adds a little meaning ('countries with tax classification') but does not explain what each list's entries look like or whether the parameter accepts only one kind at a time.

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 ('Read') and resource ('reference lists') and enumerates the four kinds of reference data returned, which clearly separates it from the entity-oriented siblings like get_article or get_voucher. It stops short of explicitly naming those siblings as alternatives, so a 4 rather than a 5.

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 phrase 'needed to fill documents correctly' implies the use case (resolving lookup values before creating/updating documents), but there is no explicit when-to-use/when-not guidance and no alternative tool is named. Usage is inferable rather than stated.

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