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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds genuinely new behavioral context the annotations lack: a per-record credit cost with a minimum of 2, and the fact that the dataset is a composite merged across seven index families. It stops short of auth/rate-limit detail, but the cost disclosure is the material trait here.

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?

Three sentences, front-loaded with what the tool is, followed by the cost constraint and then the routing alternatives. No sentence is redundant and each carries a distinct decision-relevant fact.

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 13-parameter search tool with an output schema, the description covers the pieces an agent needs that structured fields cannot supply: dataset composition, cost model, and sibling routing. Return-value format is delegated to the output schema, which exists, so nothing critical 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?

Schema description coverage is 100%, so the baseline is 3. The description goes slightly beyond the schema by tying page_size to a billing consequence ('Costs 1 credit per record returned ... keep page_size to what you need'), which reframes a plain integer as a cost driver. It adds no meaning for the index-range filters, but those are self-documented.

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 (Search) and resource (composite stored Numbeo country dataset) and adds the scope detail that it is merged from seven index families. It explicitly differentiates itself from siblings by naming datasets_numbeo_countries_item, numbeo_indices_country, and datasets_numbeo_cities_search, so an agent can place it without opening any schema.

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?

Names three concrete alternatives and the condition each serves: single stored country (countries_item), live ranking (indices_country), and city records (cities_search). This is explicit when-to-use routing rather than implied context, plus a practical sizing hint ('keep page_size to what you need').

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