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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so safety and determinism are covered. The description adds useful context (static, no chart, 36-star default flagged, magnitude trimming) but doesn't cover pagination or response shape, which the output schema carries.

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 compact sentences plus a group/cost tag; front-loaded with the key noun. The bracketed metadata lines are boilerplate but consistent with the tool family and mildly useful.

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?

For a static reference lookup with an output schema, the description covers provenance, contents, the default flag, and a trimming filter. Nothing essential is missing; only the return-format note is left to the output schema.

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% and both parameters (fields, precision) are fully documented in the schema. The description mentions maxMagnitude, a query-string option, adding a little signal, but the structured fields do the heavy lifting. 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?

States a specific resource (fixed star catalogue) and its exact provenance (Swiss Ephemeris fixstars.cat), naming the fields returned. It is clearly distinguishable from the related astroway_aspects_fixed_stars, which computes star contacts rather than listing names.

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?

"Static lookup, no chart needed" gives clear context for when to reach for it, and the maxMagnitude trimming note scopes a common use case. It does not explicitly route the agent to a sibling for the computed-star case, so it falls short of a 5.

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