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

No annotations are provided, so the description carries the full behavioral burden. It discloses the return content and the 'Paris anchor'/'travel band' model, and implies a read-only priced-city list, but says nothing about permissions, pagination, or limits.

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 tight sentences with no filler; the content of the result is front-loaded before the call condition. 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?

With no output schema, the description correctly explains the return values (priced cities, distance, travel band) and gives a usage trigger. Its only gap is omitting the optional region filter, which is minor given the schema documents it.

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% for the single optional 'region' enum parameter, so the schema fully documents it. The description adds no parameter-level detail (it never mentions region filtering), so 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 description states a specific resource (cities already priced) and the data returned (distance from the Paris anchor, travel band), and the mission-oriented siblings make the city-listing role unambiguous. The verb itself is only implied by the name, keeping it short of a full 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?

It gives an explicit trigger: 'Call this when the user names a city you cannot match, to pick the nearest listed anchor.' That is a clear when-to-use condition with a stated goal. It does not name an alternative or a when-not condition, so it falls short of 5.

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