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

The annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, covering the safety profile. The description adds the domain of data (sunrise/sunset/moon events) and the date scoping, which is useful context but not deeply behavioral. No contradictions with 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 single, front-loaded sentence that efficiently conveys the tool's essence without wasted words. It is concise and to the point.

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 the output schema exists and annotations cover safety, the description is mostly adequate. The main gap is the lack of explanation for lat/lon, which are the required parameters. Overall, it is complete enough for a simple tool but leaves one significant ambiguity.

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 exactly 50%; lat and lon lack descriptions. The description only mentions 'for a date', reinforcing the date parameter, but does not compensate for the undocumented lat/lon parameters, leaving their semantics to inference from the tool name.

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 indicates the tool provides sunrise, sunset, and moon events for a given date. While there is no explicit verb, the resource and scope are unambiguous, and the distinction from weather-related siblings like forecast or airquality is evident.

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: if you need sunrise/sunset/moon data, this is the tool. However, it does not explicitly mention when to use it over alternatives or provide any exclusions, making the usage guidance merely implied rather than explicit.

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