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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint, so the safety profile is fully covered by structured data. The description adds one genuinely useful behavioral fact beyond the annotations - the 10-credit (Tier 1) cost - but says nothing about return format, precision behavior, or limits.

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 sentence is front-loaded and wastes no words, and the bracketed group/cost metadata is compact. It is appropriately sized for a single-purpose lookup tool, though the metadata lines are formatting rather than prose.

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 no explanation, and annotations cover the safety profile. The remaining gaps are the undocumented 'longitude' parameter and the absence of any disambiguation from the very similar sibling tool, which matters given the crowded Calendar & Cycles namespace.

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 40%: 'fields' and 'precision' are documented in the schema, while 'startDate' and 'endDate' have no descriptions and 'longitude' is entirely opaque. The phrase 'within a date range' partially compensates for the two date parameters, but 'longitude' remains unexplained in both the schema and 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 specific verb ('Find'), resource ('minimum brightness moment of Algol (Beta Persei), the eclipsing variable star') and scope ('within a date range'), so the operation is unambiguous. However, it does not distinguish itself from the near-identical sibling 'astroway_calendar_algol_minimum_nearest', which an agent could easily confuse with this tool.

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 no when-to-use guidance, no prerequisites, and no exclusions. Critically, it never routes the agent between this tool and the 'astroway_calendar_algol_minimum_nearest' sibling, leaving the choice entirely to inference.

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