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

The readOnlyHint and destructiveHint annotations already signal a safe read-only operation, and the description adds relevant context: it is a 'pure reference endpoint' requiring no chart and returns catalogue-style data. It does not discuss pagination, language fallback behavior, or response shape, but those are largely covered by the parameter schema and annotations.

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 description is three sentences with no filler: it front-loads what the endpoint returns, adds a meaningful domain note about remedy elements, and closes with the key selection-relevant property that no chart is needed. Every sentence earns 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?

Given that there is no output schema, the description does a good job listing the returned star attributes and clarifying that the endpoint is a chart-free reference. Combined with the detailed parameter schema and read-only annotations, an agent has enough to invoke it correctly.

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 100%, so the parameters are already documented in the input schema. The description itself adds no parameter-level meaning, which is acceptable under the baseline of 3 for high schema coverage.

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 specific verb and resource: the tool is 'the reference catalogue of the nine flying stars' with an explicit list of fields it returns. It also differentiates itself from sibling chart-dependent endpoints by calling itself 'a pure reference endpoint that needs no chart.'

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 gives clear context: it is a reference-only endpoint that needs no chart, which tells an agent when to select it for static catalogue lookups. It does not explicitly name sibling tools or state conditions to prefer annual, monthly, or natal flying-star functions, so it stops short of full routing guidance.

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