Sun Times

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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds genuinely new behavioral facts: the POST endpoint and the 10-credit (Tier 1) cost, which matters for budget-aware agents. It stops short of noting things like the definition of 'twilight' or precision/edge behavior at polar latitudes.

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?

One front-loaded sentence captures the purpose, followed by compact tagged metadata (group, endpoint, required, cost). Nothing is padded, though the '[Required: ...]' line duplicates the schema and could be omitted.

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?

With an output schema and full annotations, most structured burden is lifted, and cost/endpoint are disclosed. Still missing for a geo/astronomy calculation are things an agent must decide on its own: which twilight bands are returned and how to pick between timezone and timezoneOffset.

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 only 40%: timezone and timezoneOffset are richly documented in the schema, but date, latitude and longitude have no prose beyond a regex pattern and types. The description merely repeats the required list rather than compensating with format, range, or hemisphere/lat-long sign conventions.

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?

Specific verb plus resource: 'Calculate sunrise, sunset, twilight times, and day length' for 'a given date and geographic location'. An agent immediately knows what it produces. It does not, however, distinguish itself from the sibling astroway_stream_sunrise_sunset, which computes much the same data in streaming form.

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 never says when to use this one-shot endpoint rather than the streaming sunrise/sunset sibling, nor any prerequisite about timezone choice. The only usage signal is the implied 'you have a date and a place', which the required-params block already conveys.

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