Cosmogram (90° Render Data)

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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description does add genuinely non-schema information: the endpoint path and a concrete cost (10 credits, Tier 1), which matters for a metered API. However it says nothing about what "render data" contains or how large the payload is, which is the key behavioral unknown here.

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 block is compact and front-loaded with the group/endpoint/cost metadata, which is efficient for a metered endpoint. But the opening sentence is under-specified relative to its brevity, and the required-fields line duplicates structured data rather than earning its place.

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 tool with 21% schema coverage, the description leaves most parameters unexplained and never clarifies how this differs from astroway_render_cosmogram. The presence of an output schema relieves it of describing return values, but the input-side and sibling-selection gaps remain substantial.

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 21% across 14 parameters. The description's "[Required: date, time, latitude, longitude]" merely restates the schema's required array, adding no semantics. Undocumented enums like the 25 houseSystem letter codes, the withTnp and cosmogram booleans, and zodiacType receive no explanation anywhere.

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?

"Ebertin cosmogram render data" names a resource (the 90° Ebertin cosmogram) but the verb is ambiguous — it is unclear whether this returns rendered image data, plot coordinates, or a computed chart. Crucially, the very similarly named sibling astroway_render_cosmogram is not distinguished, nor is astroway_cosmobiology_dial_90, so an agent cannot confidently pick this over its neighbours from the description alone.

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-shaped content is a list of required fields and a credit cost; there is no statement of when to use this versus astroway_render_cosmogram or the other cosmobiology tools. No prerequisites, no exclusions, no alternatives are offered.

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