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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds only the credit cost (20 credits, Tier 2) and the orb-scoped planet scope; it says nothing about response shape, errors, or limits beyond that.

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?

One front-loaded sentence stating the operation plus two compact metadata tags; no filler, no redundancy.

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 values need not be described, and the required birth data plus orb are covered by the schema. What remains thin is usage guidance, but nothing an agent needs to call the tool correctly 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 description coverage is 100%, with the nested birth-data and orb fields fully documented, so the baseline is 3. The phrase 'within orb' loosely ties to body.orb but adds no format or default detail beyond the schema.

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?

Names a specific verb (Calculate) and a precise resource (parallel and contra-parallel aspects by declination), and defines both terms, so an agent can distinguish it from ecliptic-aspect siblings like aspect_bar or midpoints. It does not explicitly name an alternative sibling, keeping it short of a 5.

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 scope (all planets, within orb) implies when the tool applies, but there is no explicit when-to-use/when-not guidance or routing to sibling aspect tools. Usage must be inferred from the astronomical term alone.

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