Natal Chart

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

Annotations already cover read-only/idempotent safety, so the description's value is in the extra behavior it discloses: unknown time yields null houses/angles/sect plus a timeUnknown block with the Moon's daily range, and ?lang= adds a localized map keyed by English names. That is genuine response-shape context beyond the annotations, though cost (20 credits) and sidereal/tropical output differences go unmentioned.

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?

Three tight sentences, front-loaded with what gets computed, then the edge case, then localization. No filler; slightly dense but every clause carries information.

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 14-parameter core computation with an output schema, the description handles the hardest case (unknown time) and localization well, but omits the zodiac/house-system selection logic and coordinate/time-format expectations. Adequate to call it, not enough to call it correctly without reading the 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 only 21% across 14 parameters. The description explains timeUnknown and the ?lang= query param, but leaves zodiacType, ayanamsa/ayanamsaId, houseSystem (25 enum codes), cosmogram, name, city and date/time format undocumented — including the sidereal-vs-tropical choice that determines the whole result. Far too much is left to the bare 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?

States a specific verb and resource ('Calculate a full natal chart') and enumerates the outputs (planets, house cusps, aspects, sect, angles) for a birth moment. That distinguishes it from narrower siblings like astroway_western_planets or astroway_calendar_houses, though no sibling is named explicitly.

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 description clearly routes one case — unknown birth time → send timeUnknown: true — which is a real usage rule. But it gives no guidance on when to choose this tool over astroway_western_planets, astroway_vedic_kundli, or astroway_render_wheel_western, and no prerequisites or exclusions.

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