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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile carries little weight here. The description adds real context about output content — the day-to-day change in day length and a link that opens the same calendar on one printable A4 page — but says nothing about defaults, missing-place behavior, or error conditions.

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 puts the core resource and scope first. The trailing 'with the change of the day length from day to day' clause is slightly clunky and the print-link aside is tacked on, but no sentence is wasted.

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?

An output schema exists, so return values need not be explained, and parameters are fully covered by the schema. The main remaining gap is routing relative to the six sibling tools, especially sun_times and find_city, which the description never mentions.

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 six parameters (including the pl/en enum and the YYYY-MM month format) are already documented in the schema. The description only adds the vague phrase 'at a place' and contributes no additional meaning about how tz/lat/lon/city interact or which combinations are valid.

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 concrete resource and scope: sunrise, sunset and day length for every day of a month at a place. This implicitly separates it from the single-day sibling sun_times, but no sibling is named, so the differentiation is inferred rather than stated.

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 phrase 'for every day of a month' implies when this is preferable to a per-day tool, but there is no explicit when-to-use, when-not, or alternative named (e.g. sun_times for a single day, find_city for resolving place names). Usage must be inferred.

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