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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the tool is clearly a safe read operation. The description adds specific return fields (sunrise, sunset, etc.) but does not disclose default date behavior or rate limits. This is adequate given annotation coverage.

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?

Single sentence that front-loads the key outputs and states the tool's scope ('any location and date'). Every word is necessary; no superfluous content.

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?

Tool is read-only with two well-documented parameters and an output schema (not shown but present). The description covers what the tool returns and its scope. Minor omission: no mention that date defaults to today, but overall sufficient given supporting metadata.

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?

Input schema describes both parameters (q and date) with full coverage (100%). The description does not add new semantic details beyond what the schema provides, so baseline score of 3 applies.

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 tool retrieves sunrise, sunset, moonrise, moonset, and moon phase data for any location and date. The verb 'get' and specific resource 'astronomy data' match the tool's title and distinguish it from siblings like current weather or forecast tools.

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?

No explicit guidance on when to use this tool versus alternatives (e.g., weather.weatherapi.current or usno.astronomy.sun_moon). The description implies it's for specific date queries but does not mention when not to use it or compare capabilities.

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