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

Annotations already declare readOnly, idempotent, openWorld=false and non-destructive, so the safety profile is covered. Beyond that, the description adds genuinely useful context: the upstream data source (NOAA Kp index) and the shape of the answer (per-region intensity, Kp thresholds, current Kp, multi-day forecast). It does not address data freshness or caching, which keeps it below a 5.

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?

It is a single dense run-on sentence with nested clauses and parenthetical enumerations, which makes it harder to parse than a short front-loaded statement plus supporting detail. Nothing is redundant, but the structure could be split for scanability.

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, full schema coverage and rich annotations, the description only needs to establish scope, data source and output categories, and it does all three. The remaining gap is behaviour with zero arguments (presumably all regions) and forecast horizon, which is not stated.

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?

The description hints at the two location modes ('north, centre and south of Poland or in a given city'), which loosely maps to the city vs lat/lon parameters, but it adds nothing about the lat/lon pairing semantics, the nearest-seat behaviour, or the lang option. With 100% schema description coverage, the schema already carries this load, so baseline 3 applies.

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 names a concrete verb+resource (aurora visibility in Poland tonight) and its data source (NOAA Kp index), and enumerates the outputs: intensity level per region or city, required Kp, current Kp and a multi-day forecast. This clearly separates it from siblings like planets_tonight or iss_passes, which concern other sky objects.

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?

Usage is implied by the strong topical framing (tonight's aurora in Poland), but there is no explicit when-to-use/when-not guidance and no sibling is named as an alternative or complement. An agent must infer that this is the tool for aurora questions from the purpose statement alone.

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