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

No annotations are provided, so the description carries full burden. It discloses time precision ('seconds vs Swiss Ephemeris, stations ~1 min'), and details on eclipse reporting (global vs local circumstances). It does not mention authentication, rate limits, or side effects.

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?

Description is a single dense paragraph, but efficiently packs all necessary information. It front-loads the main purpose and then details requirements. Minor improvement could be structuring with bullet points, but overall concise and informative.

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?

Despite lacking an output schema, the description explains what return values to expect for each event kind (e.g., global vs local circumstances for eclipses, horizon info for moon). It covers precision and coordinates needed, making it self-contained for an agent to understand inputs and outputs.

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 coverage is 100%, so baseline is 3. The description adds significant value beyond schema by explaining parameter dependencies (e.g., lat+lon required for certain kinds), eclipse details, and precision notes. This goes beyond simply restating schema fields.

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?

Description clearly states 'Sky events in a UTC date range' and lists specific event types (rise/set/transit, lunar phases, eclipses, stations, crossings). It explicitly distinguishes each kind's requirements, making the tool's purpose specific and actionable.

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?

Description explains when each event kind is available and what parameters are needed (e.g., 'need lat+lon+body' for rise/set/transit). It also mentions the date range limit (<=370 days). However, it does not explicitly state when to avoid this tool or suggest alternatives among siblings.

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