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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds useful cost metadata (10 credits, Tier 1) and group context, but does not disclose timezone defaults, coordinate conventions, or other operational behavior beyond what the schema provides.

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 states exactly what is calculated and for what inputs, followed by only compact metadata tags. Every element is purposeful and there is no redundant 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 not be explained, and annotations cover the safety profile. The description is sufficient for selection and invocation, though it does not mention timezone behavior or coordinate conventions that the schema handles in detail.

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 57%; the four optional parameters have detailed schema descriptions, while the three required ones lack schema descriptions. The description compensates conceptually by naming date and 'geographic location,' but adds no format, range, or unit detail beyond that.

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 uses a specific verb, 'Calculate,' and names exact resources: sunrise, sunset, twilight times, and day length, scoped to a date and geographic location. This uniquely distinguishes it from other astrological sibling tools, which cover charts, calendars, horoscopes, and renderings rather than solar time events for a location.

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 explicit when-to-use guidance, no exclusions, and no alternatives to compare against. The phrase 'for a given date and geographic location' supplies context but not selection guidance.

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