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 is covered. The description adds one genuinely useful behavioral fact — the results are 'approximate' — but the returned field list is redundant with the output schema and it says nothing about precision limits or that times are solar time rather than local time.

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?

Two tight sentences with the purpose front-loaded and no filler. The trailing list_bundles cross-reference is marginally useful but slightly dilutes an otherwise efficient definition.

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 two-parameter pure calculation with full schema coverage, an output schema, and safety annotations, the description covers what is needed. The only real gap is not flagging that the returned times are solar-time values (and hence not directly local clock times), which matters for correct interpretation.

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% and both parameters carry their own descriptions with ranges (latitude in degrees, day of year 1-365), so the schema does the heavy lifting. The description merely names the same two inputs and adds no unit, sign-convention, or edge-case detail beyond the schema.

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 and resource ('Approximate sunrise and sunset times') plus the two inputs that drive the computation, so an agent knows exactly what it computes. It does not, however, differentiate itself from the sibling 'calculate_sunrise_approx' or 'calculate_sun_exposure', which an agent scanning this large tool family would need.

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 when-to-use or when-not-to-use guidance, and no mention of how this differs from the near-duplicate sibling calculate_sunrise_approx. The pointer to list_bundles is a discovery aid for related calculators, not usage guidance for this tool.

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