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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and network profile is covered. The description adds no behavioral context beyond that: it does not describe the return shape, data recency, coverage gaps, or any auth/rate-limit considerations.

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?

A single tight sentence with no filler; the resource and the permissible index values are front-loaded. It is efficient, though the fragmentary noun-phrase style leaves the action slightly implicit.

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?

The tool is a simple two-parameter lookup with a full output schema and 100% schema description coverage, so little extra prose is required. Still, the description gives no indication of what the returned indices represent or how to choose between this and the sibling numbeo index tools, leaving it only minimally adequate.

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 coverage is 100%, so both required parameters (slug and index) are fully documented in the schema. The description restates the index family enum values but adds no slug format, casing, or lookup guidance beyond the schema example. Baseline 3 is appropriate.

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 phrase 'Numbeo city data for an index family' names a specific resource (city-level index data) and enumerates the index families it covers, and the 'city' scope implicitly distinguishes it from the country/rankings siblings. However, it uses a noun phrase with no verb, so it stops short of the verb+resource precision of a 5.

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?

There is no when-to-use guidance and no mention of alternatives such as numbeo_indices_country, numbeo_indices_rankings, or numbeo_cost_of_living_city. An agent must infer selection purely from the tool name and the index list.

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