units.time_small_convert

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

Annotations already cover the safety profile (readOnly, idempotent, closed-world), and the description adds real context beyond them: case-sensitive unit strings, a Decimal-string magnitude, and the fixed 1 day = 86400 s convention. It stops short of saying what happens on an unknown unit (error vs. fallback) or whether results are rounded, which are the remaining behavioral gaps.

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?

Three sentences, front-loaded with the capability, then the input conventions, then the exclusion. Every sentence supplies a fact an agent needs; nothing is restated from the schema or annotations.

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 present, return values need no explanation, and the description covers the input contract and the unsupported-unit edge case. The only shortfall is error behavior for invalid or out-of-range input, which an agent would still have to discover at call time.

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 coverage is 0% — all three parameters are bare 'string' fields with no enum — so the description carries the full burden. It does compensate well by supplying the accepted unit domain for from_unit/to_unit and specifying magnitude's expected format (Decimal string) and case sensitivity, though it does not state whether magnitude must be positive or what an out-of-domain unit yields.

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+resource ('시간 단위 ... 사이를 pint 로 변환한다') and enumerates the exact unit set (s, ms, us, ns, ps, min, hour, day). It also carves out the cases it does not handle (월/연), which makes it distinguishable from the datetime.* siblings at a glance.

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?

Explicitly says months and years are unsupported because their length is not fixed, and routes the agent to datetime.diff for date intervals. That is a concrete when-not plus a named alternative, not implied usage.

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