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

Annotations already state readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely useful behavior beyond that: DST is resolved against the supplied date, multiple targets are supported, and the date defaults to today in the origin place. What it omits is how unresolvable place names are handled, which matters given openWorldHint=true.

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 tight parts — a front-loaded purpose sentence, a 'Use when:' trigger list, and a ready-to-adapt example payload. Every sentence earns its place and nothing is repeated.

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 4-parameter tool with full schema coverage and complete annotations, the description covers purpose, triggers and an example. It lacks any indication of the response shape (per-place times, UTC offsets, date rollover across midnight), which is the one gap for a tool with no output schema.

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 each parameter (time, from, to, date) is already documented with formats and examples. The description's example object reinforces how the parameters combine, but adds no syntax or constraint detail the schema does not already carry, so the baseline of 3 applies.

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 gives a specific verb and resource ('Converts a local time from one place to one or more other places') plus a scope qualifier ('handling daylight saving on that date'). It is clearly a time-conversion tool, though it never names the sibling world_time or explains how it differs from it.

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 explicit 'Use when:' clause with two natural-language scenarios ('15:00 in Paris is what time in New York?', 'schedule a call at 9 am San Francisco for London and Tokyo') gives the agent concrete trigger conditions. There are no exclusions or stated alternatives, 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.