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

With readOnlyHint and openWorldHint already declared, the description adds genuinely new behavioral context: output is calculated geometry only with no interpretation or prediction, and calls cost $0.02 USDC after 25 free per day. That pricing/allowance disclosure is exactly the kind of operational detail annotations cannot carry.

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 definition is front-loaded in the first sentence, with acronym expansion and cost following in logical order. The 'useful for mapping, visualization, geographic research, and location-aware planning' sentence is the only soft filler, but it is short enough not to be wasteful.

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?

There is no output schema, and the description covers the return only at a high level ('bounded GeoJSON loci', geometry without interpretation). Combined with the unresolved question of how the angular condition is selected or whether all four are returned per body, an agent still lacks enough to predict the response shape.

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 100%, so instantUtc format, the 1-4 body limit, and _payment are already documented; the description correctly echoes the one-to-four-body constraint. But it introduces an ambiguity the schema cannot resolve: the 'named angular condition' (AC/MC/DC/IC) has no corresponding input parameter, so an agent may hunt for an argument that does not exist.

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 precise verb and resource: it calculates bounded GeoJSON loci on Earth where selected bodies sit at a named angular condition at one UTC minute. Defining AC/MC/DC/IC inline lets an agent distinguish this geometry-output tool from siblings like celestial_state or celestial_relations without opening a schema.

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 offers use-case framing (mapping, visualization, geographic research, location-aware planning), which implies when the tool fits. However, it never names an alternative sibling or states when-not to use it, so an agent must infer the boundary against celestial_state or celestial_event_window on its own.

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