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

With no annotations at all, the description carries the full burden, and it only partially meets it: enumerating the returned fields is valuable given there is no output schema. However, it says nothing about permissions, rate limits, behavior at polar latitudes where sunrise/moonrise may not occur, or what happens when 'port' and 'lat'/'lon' are both supplied or both omitted.

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?

A single front-loaded sentence that spends its words on the enumerated output fields rather than filler. The colon-and-list structure is scannable, though the list is dense and unsorted relative to the time-of-day sequence.

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?

For a 5-parameter tool with no annotations and no output schema, the enumeration of return fields compensates reasonably well for the missing output schema. Critical gaps remain around the port-versus-coordinates relationship and edge-case behavior (polar day/night), which an agent would need before calling it confidently.

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 the schema already documents each of the five parameters including defaults and the 1-7 day cap. The description adds no meaning beyond that, so the baseline 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?

States a specific verb ('Get') and resource ('sun and moon data') and enumerates the exact fields returned, so an agent knows precisely what this tool delivers. It does not explicitly distinguish itself from siblings such as get_weather or get_tides, leaving differentiation to inference, which keeps it just below 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?

There is no guidance on when to use this tool versus get_weather, get_conditions, or get_tides, nor on how to choose between the lat/lon pair and the 'port' parameter. All five parameters are optional, and the description offers no hint about which combination is expected.

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