openaq_countries

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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is fully covered. The description's only added behavioral fact is the scoping constraint (only countries with data), which is genuinely useful but thin; nothing about result size, ordering, or whether the list is exhaustive.

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 sentence, front-loaded with the verb and resource, and no filler. It could carry one more clause (what the list is used for) without becoming bloated, but nothing present is wasted.

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 zero-param, read-only list endpoint with full annotation coverage and no output schema, this is adequate but minimal: it does not say what fields come back (codes vs names) or that the output feeds the other openaq_* tools, which is the main reason an agent would call it.

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?

Zero parameters, so baseline is 4. The description correctly implies the tool takes no input, matching the empty schema, and adds no misleading parameter expectations.

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?

Specific verb ('List') plus resource ('countries') with an added qualifier: only countries that have air quality data on OpenAQ. That distinguishes it from openaq_air_quality and openaq_measurements in substance, but it never names those siblings explicitly.

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?

No statement of when to call this versus the other OpenAQ tools, no mention that the result is typically a discovery step to obtain country names/IDs for the measurement tools. Usage is only implied by the word 'List'.

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