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

Annotations already declare readOnly/idempotent/non-destructive, so the description's added value is the NASA NeoWs provenance, the hard seven-day window limit, the Polish-time convention, dual distance units, and the sort order. It stops short of covering empty-result behavior or failure modes, but the established behavior well exceeds the annotation baseline.

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 front-loaded sentence that leads with the resource and scope before piling on return-field details, with zero filler. The nested parentheses carry real information but make it dense to parse in one pass, keeping it just shy of a 5.

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 a full output schema and safety annotations, the description only had to supply source, units, timezone, sort order, and range limits, all of which are present. Only error/empty-edge behavior is unaddressed, which is minor for a read-only listing tool.

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 every parameter already has documentation, and the description only restates the defaults (today plus six, seven-day cap) and the Polish-time default rather than adding new syntax or edge-case meaning. Per the coverage rule, baseline 3 is appropriate with this level of marginal reinforcement.

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 the exact resource and scope ('asteroids and comets passing Earth between two dates') and enumerates the returned fields (closest approach time, distance in km and lunar distances, speed, size, hazard flag). No sibling tool in the list (aurora_forecast, iss_passes, planets_tonight, etc.) could be confused with this one.

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 concrete context for use: a date range is required, capped at seven days, and defaults to today plus six when omitted, and results come closest-first. It does not explicitly say when to prefer a sibling (e.g., tonight_sky for general sky content), but the domain is narrow enough that no overlap inference is needed.

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