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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds the useful constraint that it honors the same filters as the search tool, but says nothing about the return shape or aggregation behavior beyond the generic 'terms aggregation counts'.

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 sentences, front-loaded with the core behavior and immediately followed by the usage cue. No padding or restatement of the name.

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, complete parameter documentation, and annotations carrying the safety profile, the description only needs to establish purpose and usage, which it does. It could optionally note which facet dimensions are aggregatable, but the schema already constrains facet to 'country'.

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 all 15 parameters are already documented, including the required 'facet' enum value and the index-range filters. The description adds only the high-level note that filter semantics match the search tool, which is context rather than new per-parameter detail.

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 and resource: 'Returns terms aggregation counts for the Numbeo cities dataset.' It differentiates from the sibling by framing itself as the facets companion to 'the related search tool,' though it does not name datasets_numbeo_cities_search 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?

'Use alongside the related search tool to inspect filter counts under the same query filters' clearly conveys the scenario for calling it, and 'honoring the same filters as Search the Numbeo cities dataset' ties it to the companion query. No explicit exclusions, but the intended use is unambiguous.

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