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

Annotations already declare the tool as read-only, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds useful scope details such as defaulting to today and including next new/full moon data, but it does not disclose any further behavioral traits like timezone handling or resolution behavior.

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 a single, front-loaded sentence that immediately names moonrise and moonset before listing additional outputs. It is efficient and contains no filler, though the list of outputs makes it slightly dense.

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?

The tool has a rich input schema, full parameter descriptions, an output schema, and clear annotations, so the description need not explain return formats or safety behavior. It is complete enough for an agent to understand the tool's scope, though it could mention how location inputs are selected (city vs. lat/lon/tz) if that were not already in the schema.

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 schema already documents every parameter, including city, lat/lon, tz, date, and lang. The description only restates the date default implicitly via 'today by default' and adds no new syntax or constraint details beyond the schema.

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 resource and scope: moonrise/moonset at a place on a day, plus phase and related lunar events. It is clear what the tool returns, but it does not explicitly distinguish itself from the sibling moon_phases tool, which likely overlaps on phase data.

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?

Usage is implied by the description: use it for moonrise/moonset and lunar phase information for a place and day, with today as the default. There is no explicit when-to-use guidance, no mention of alternatives like moon_phases, and no exclusion conditions.

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