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

Annotations already declare readOnly and non-destructive behavior. The description adds meaningful context beyond that: the result is a fixed set of 24 countries, the output includes specific fields, and the data is scoped to aggregated public surveillance only. This is non-obvious behavioral information not present in the schema or annotations.

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?

Two tightly written sentences. The first conveys the action and result contents, the second adds a scope guardrail. There is no filler or redundancy; every phrase 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 parameterless list tool with no output schema, the description fully specifies the content of the list (24 countries, English/German names, source) and the scope boundary (aggregated surveillance only). Nothing an agent needs to decide whether to call it is missing.

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 has zero parameters, so the baseline of 4 applies. The description correctly does not waste space on parameter explanations since none exist.

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 uses the specific verb 'List' and names the exact resource ('the 24 countries InfectRisk covers') with the included fields (English and German names, surveillance source). It also distinguishes itself by stating what it does not cover (case numbers or personal risk), making it clearly distinct from the infection activity and outbreak siblings.

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 a clear boundary: 'Scope is aggregated public surveillance data only, never case numbers or personal risk.' This tells an agent when not to use this tool, but it does not explicitly name the sibling tools as alternatives. The context is clear enough for a simple list tool, though explicit sibling routing would push it to a 5.

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