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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: the ranking logic, the curated-interpretation return, and the [Cost: 50 credits (Tier 3)] disclosure. It loses credit because it claims '11 languages' while the schema's language enum exposes 21, an internal inconsistency that could mislead an agent about coverage.

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 carry the core behavior, with the ranking rule front-loaded, followed by structured [Group] and [Cost] metadata lines that are easy to scan. Nothing is wasted, though the '11 languages' clause is inaccurate rather than merely brief.

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?

An output schema exists and the input schema is fully documented, so return-value explanation is unnecessary. For a read-only geo tool sitting in a family of six similar astroway_geo_acg* tools, the description is adequate on behavior but incomplete on routing, which is the main thing an agent needs here.

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 100% and the nested body schema already documents date/time/latitude/longitude, timezone handling, category, polarity, radiusDeg, and language in detail. The description's only parameter-adjacent contribution is the optional 'point' behavior for proximity ranking, 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 specific resource and scope: A*C*G lines filtered to one life category, with a stated ranking rule (astrological weight, then proximity when a point is supplied). It does not, however, differentiate itself from close siblings such as astroway_geo_acg, astroway_geo_acg_categories, or astroway_geo_acg_line_report, so an agent cannot tell from the text alone which of the six geo_acg tools to pick.

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?

The only usage signal is the conditional clause 'when a point is supplied, by proximity to it,' which hints that a location is optional but never states when to choose this tool over astroway_geo_acg or astroway_geo_acg_categories. There is no when-to-use, when-not-to-use, or prerequisite guidance, and the sibling list is crowded with near-duplicates.

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