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

No annotations are provided, so the description must fully disclose behavior, and it does: it states exact arithmetic, refusal of nonexistent dates instead of rounding, the response shape {count, ok, results}, order preservation, and the calendar-spec cost model. This is far beyond minimal and gives the agent a reliable mental model of side effects, limits, and error behavior.

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 core purpose is front-loaded and the content is organized into input, batching, response, exactness, and error handling. Some redundancy exists — the calendar-spec cost point is made twice — and the all-caps plural instruction adds emphasis but also length. Overall, it is well-structured for a tool with this complexity.

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 tool with no output schema, no annotations, nested objects, and 9 parameters, the description covers the essentials: accepted input combinations, batching, limits, return envelope, exactness, and failure behavior. The main gaps are the undocumented 'time' and 'on_error' parameters and the lack of a detailed result-schema breakdown, but the description is still strong enough for correct invocation in most cases.

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 0%, so the description must compensate. It explains the singular/plural input constraint, which parameter groups are mutually exclusive, the role of calendar, batching semantics, and general output behavior. However, it does not clarify the 'time' or 'on_error' parameters, which remain underspecified even though they are in 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?

The description opens with a specific action, 'Convert between a calendar date, its day number, and its Gregorian date,' clearly identifying both the operation and the resource. It further distinguishes the tool by stating that all three forms are returned together, along with leap-year, year-length, and named-period information. This is enough to separate it from siblings like parse_calendar_date or format_calendar_date.

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 gives concrete usage guidance: provide exactly one of date, day_number, gregorian, or their plurals, and use plurals when handling multiple dates. It also explains batching preferences and the 1000-item limit. It does not explicitly name sibling tools or state when to prefer an alternative, so it stops short of a 5.

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