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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the safety and determinism profile is covered structurally. The description adds genuinely useful non-annotation context: the cost (10 credits, Tier 1), the endpoint, and the required inputs. It says nothing extra about behavior 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?

A single front-loaded sentence carries the meaning, followed by compact bracketed metadata (group, endpoint, required params, cost). Nothing is padded, though the bracket lines are mechanical rather than additive.

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, so return values need not be explained, and annotations cover safety. However, for a 7-parameter tool with low schema coverage and obscure domain output ('geodetic chart degrees'), the description leaves the agent without enough to pick the right method or parse the result relative to sibling geo tools.

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 29%, so the description is expected to compensate, but it explains only the method ('Sepharial method') and even then omits the alternative enum value 'johndro'. Parameters like obliquity, year, precision, and fields get no added meaning from the description.

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 states a concrete verb+resource pair ('Convert geographic coordinates to geodetic chart degrees') and names the Sepharial method, so the agent knows what the tool computes. It does not, however, distinguish it from other coordinate-to-chart geo siblings such as astroway_geo_acg or astroway_geo_zenith, leaving the boundary between them to inference.

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?

It lists the required parameters and endpoint but gives no when-to-use guidance, no exclusions, and no mention of when to prefer this over other astro-geography tools. The agent must guess whether this is the right geo tool for a given request.

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