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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=falseasi, so the safety profile is known. The description adds valuable behavioral context beyond annotations: licensing (CC BY 4.0 + NLOD 2.0), no auth, no upstream cost, UTC offset support, and polar day/night handling. This is meaningful additional disclosure without contradicting the 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 a well-structured single paragraph that front-loads the core purpose, then cleanly separates sun and moon outputs, and ends with licensing and coverage. Every sentence provides useful information with no redundancy or fluff.

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 an output schema exists (not shown but indicated), the description need not explain return values. It covers the essential operational aspects: global scope, any date, sun and moon outputs, UTC offset, polar day/night, licensing, auth-free access, and no cost. This is complete for an agent to invoke the tool 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 all five parameters are already well-documented (lat, lon, body, date, offset). The description adds a summary of outputs for sun vs moon and mentions UTC offset support, but it does not significantly go beyond what the schema already provides. Baseline 3 applies due to 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 clearly states the verb 'Get' and the resource: sunrise, sunset, solar noon, and solar midnight times for any global coordinate and date. It further details the specific outputs for both sun and moon, making it easy to understand what the tool does. However, it does not explicitly name or differentiate from sibling tools like sunrisesunset.astronomy.daily, so it lacks the explicit sibling differentiation required for a 5.

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 implies usage for any global coordinate and dateainer and highlights polar day/night support, which gives context on when it is appropriate. But it does not explicitly state when to use this versus alternatives or mention any exclusions, so it only reaches 'implied usage' rather than clear guidance.

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