numbeo_cost_of_living_rankings

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

With no annotations provided, the description carries the full burden, and it does so well: it discloses data freshness behavior ("continuously-updated" vs "historical periodic snapshot"), credential requirements ("Credential-free"), and the data source (numbeo.com). It does not mention rate limits, pagination, or output format, but for a read-only ranking retrieval these are minor gaps.

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, zero filler. The first sentence front-loads the purpose, and the second packs the index list, mode distinction, and credential/source info efficiently. Every clause earns its place.

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 simple 2-parameter, fully-schema-covered read tool with no output schema, the description is largely complete: it names the returned indices, the two access modes, and the auth/source context. It does not describe the output structure or period format nuances beyond the schema, but the schema already carries the period example, 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% — both scope and period are already documented with descriptions and an example format. The description goes further by clarifying what the enum values mean semantically: "current" is the continuously-updated index and "historical" is a periodic snapshot, adding meaning beyond the bare enum labels.

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 states a specific verb and resource: "Get the global Numbeo cost-of-living city ranking." It enumerates exactly which indices are included and the global city-level scope, which distinguishes it from sibling country-level tools like numbeo_cost_of_living_rankings_by_country and per-city tools like numbeo_cost_of_living_city. An agent can select this tool confidently without opening schemas.

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?

The description gives clear context: it is the global city-ranking tool, and it explicitly explains the two operating modes ("continuously-updated current index or a historical periodic snapshot"), which maps directly onto the scope parameter. It also notes "Credential-free public Numbeo data," signaling no auth setup is needed. It does not explicitly name alternatives or when-not-to-use conditions, so it stops short of a 5.

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