Horizon Chart

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 genuinely useful operational context not present in annotations: the POST endpoint, the credit cost (50 credits, Tier 3), and the required inputs. It does not clarify an important behavioral question, namely whether only planets currently above the horizon are returned or all planets with horizon coordinates, which matters for interpreting the result.

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?

The core sentence is front-loaded and wastes no words. The bracketed metadata lines are compact and each carries information (group, endpoint, required inputs, price), though they slightly dilute the prose.

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 13 parameters at 23% coverage and multiple astrological configuration switches, the description is too thin: an agent cannot tell how ayanamsa, zodiacType, or houseSystem affect the output, nor which coordinate convention the returned azimuth uses. The output schema and annotations cover return structure and safety, but the invocation-level ambiguity is left unresolved.

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 only 23% across 13 parameters, so the description must compensate and does not. It restates the four required fields (already encoded in the schema's required array) and never explains the undocumented optional parameters such as cosmogram, zodiacType, houseSystem, city, or name. The agent gets no help on how the sidereal/tropical and house-system options shape a horizon calculation.

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 verb and resource: computing azimuth and altitude of planets above the local horizon at a given time and place. That clearly separates it from siblings like astroway_specialized_heliocentric or astroway_specialized_harmonics, though it never explicitly contrasts with nearby geo tools such as astroway_geo_local_space or astroway_geo_zenith, which an agent may also consider.

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?

There is no when-to-use or when-not-to-use guidance and no named alternative. The metadata block lists required fields and cost but says nothing about which selection context should send an agent here instead of a sibling chart tool.

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