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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true, so the safety profile is covered. The description still adds real behavioral context beyond annotations: it discloses that the output is a catalog, that it is not a geolocation tool, and that IDs must not be guessed and homonyms must be disambiguated. It does not describe pagination or result-size behavior, so it stops short of a 5.

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 trigger condition is front-loaded, followed by an example, then a parameter note and a scope limitation. Every sentence earns its place and there is no filler.

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?

With an output schema present, the description need not explain return values; it instead covers the things structured data cannot: when to call it, how the ID feeds into a downstream city_filter, the no-guessing rule, and the explicit negative scope (no user geolocation). Complete for a two-parameter lookup tool.

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 baseline is 3. The description adds functional meaning beyond the schema by explaining that country_code scopes the returned cities to the selected country, clarifying the parameter's effect rather than merely restating its format.

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 names a specific resource (geographic catalog of cities/countries) and states its function: resolving a name to a country or city ID for use in vacancy search. It explicitly contrasts its scope with sibling vacancy tools by noting it 'returns a geographic catalog; it does not determine the user's location.' An agent can distinguish it from get_vacancies/search_vacancies immediately.

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?

It gives an explicit trigger ('use when you need to determine a country or city ID by name'), a concrete worked example ('searching vacancies in Moscow requires city_filter with the ID from this response'), and a clear rule against guessing IDs plus a homonym disambiguation instruction. Nothing about when to select this tool is left to inference.

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