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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is covered. The description usefully adds the 'single nearest ... before or after' semantics, but omits tie-breaking (if the date sits equidistant between two minima) and any auth/cost behavior beyond the credit tag.

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 stating the core behavior, followed by compact Group and Cost tags. No padding or redundancy, though the metadata lines slightly dilute the one-line payload.

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 the core lookup is stated. But for a 4-parameter tool with an unexplained 'longitude' input and no clarity on how 'nearest' resolves ties, the definition is only minimally complete.

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?

With only 50% schema description coverage, the description carries real burden it does not meet: the 'longitude' parameter is entirely undocumented anywhere, and 'date' has only a pattern, not a stated meaning or timezone/format convention. The description adds nothing to clarify these parameters.

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 gives a specific verb (find) and a precise resource (the single nearest Algol brightness minimum relative to a date), which is clear on its own. It does not, however, differentiate itself from the sibling astroway_calendar_algol_minimum, so an agent must infer which of the two Algol tools to pick.

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 explicit when-to-use guidance or mention of alternatives. The phrase 'before or after a given date' implies a proximity lookup, but nothing tells the agent when to prefer this over the plain Algol minimum tool or what input conditions apply.

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