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

With no annotations, the description carries the full burden of behavioral disclosure. It mentions the UTC day-of-year range but does not specify whether the tool depends on the current time, whether any of the 9 optional parameters affect the result, or whether the call is read-only. This is a minimal disclosure that leaves key behavior implicit.

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 description is short, front-loaded with the output type, and contains no filler words. It is under-specified, but as a standalone statement of the returned value it is efficient and to the point.

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?

Given 9 optional parameters, no annotations, and no output schema, the description is incomplete. It does not clarify which parameters are relevant, how the result is computed, or whether the tool is a safe read-only operation. The agent would still need to make several unstated assumptions 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 baseline is 3 even though the tool description adds no parameter mapping or usage explanation. The description does not clarify why there are 9 irrelevant-looking optional parameters or whether any of them are meaningful, so it adds no value 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?

The description 'UTC day of year 1-366' conveys the output domain and UTC scope, but lacks an explicit verb such as 'returns' or 'gets'. It is more of a noun phrase than a clear statement of what the tool does, and it does not say whether it computes the current day of year or converts a given 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?

There is no guidance about when to use this tool versus siblings like utc-time, timezone, or iana-zones. The description does not state prerequisites, alternatives, or exclusions, leaving the agent to infer usage from the name alone.

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