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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so credit goes to what the text adds: the fixed twelve-month horizon, the Poland-only geographic restriction, Polish-time maxima, an 18-city breakdown, and moon-interference reporting. These are real behavioral constraints an agent would not know from the annotations alone.

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 information-dense sentences with the scope front-loaded and no filler. The second sentence ('With a shower ... only that one, and for the six main ones ...') is slightly elliptical and takes a second read, costing a point but not wasting space.

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, return-format explanation is not required, and annotations carry the safety profile; the description supplies the geographic, temporal, and structural scope that schema and annotations cannot. Nothing essential for a correct call 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 coverage is 100%, so baseline is 3, but the description goes further by explaining the consequence of supplying 'shower' — output narrows to one shower and, for the six main ones, expands to per-city nights. It also seeds example identifiers (perseids, geminids, Leonidy), reinforcing the enum beyond the schema list.

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 specific resource (the twelve main meteor showers), scope (seen from Poland, next twelve months), and enumerates the returned fields (activity, maximum in Polish time, ZHR, best hours, moon interference). This is clearly distinguishable from siblings like planets_tonight or iss_passes without opening any 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 implicitly explains the two calling modes — no argument returns all showers, passing a shower returns just that one (with per-city nights for the six main ones) — but it never says when to pick this tool over tonight_sky or other sky-event siblings. Usage is inferable but there is no explicit alternative routing or exclusion.

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