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

Annotations already mark it read-only and non-destructive; the description adds substantive behavior beyond that: no persistence ('Saves nothing') and a concrete error taxonomy (ambiguous_city, city_not_supported, unknown_city, city_country_mismatch). It does not contradict readOnlyHint.

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, front-loaded with the core validation purpose and followed by side-effect and error behavior. No redundant restatement of the title.

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 present, the description does not need to explain return values, and annotations cover safety. It supplies the important dry-run and error behavior; the remaining gap is input explanation, not return or safety.

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 reported at 0%, so the description must carry parameter meaning, but it only refers to 'these cities' and never explains the locations array format or the optional country_code semantics. The error names hint at city/country validation but do not define the inputs.

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 validation-only purpose tied to a named sibling: it reports whether set_radar_filters would accept the cities. The explicit 'saves nothing' distinction makes the tool identifiable without opening the 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?

It clearly frames this as a preflight/dry-run alternative to set_radar_filters by explaining that it saves nothing and returns the same rejection errors. It does not spell out an explicit when-not-to-use condition, but the alternative and selection context are clear.

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