Convert a time between zones

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

With no annotations provided, the description carries the behavioral burden and does a solid job: it explains that the input is wall-clock unless it has an offset or trailing Z, that every zone in to_zones is produced, that day changes are marked, and that the UTC instant is included. It does not mention failure behavior for nonexistent times, though the schema's gap parameter covers that.

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 with no filler. The main behavior is front-loaded, the wall-clock caveat is second, and the example is last. Every sentence contributes either action, semantics, or an illustration.

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 the moderate complexity of five parameters and no output schema, the description covers the essential behavioral contract: inputs, natural-language support, day-change marking, and UTC instant. It does not spell out the exact output shape, but it gives enough for an agent to understand what results to expect.

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 100%, so the baseline is 3, but the description adds meaningful semantics beyond the schema: it clarifies the interpretation of the 'time' parameter ('wall-clock in from_zone unless it carries an offset or a trailing Z') and gives a natural-language example ('3pm tomorrow works'). It also makes explicit that to_zones is exhaustive ('every zone').

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 verb and resource: 'Convert one time from from_zone into every zone in to_zones.' It clearly distinguishes this from sibling tools like 'now' or 'overlap' by framing it as a timezone conversion with day-change and UTC-instant output.

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 clear context for when the tool applies: converting an arbitrary wall-clock time across zones, including natural-language inputs. It does not explicitly name alternatives or exclusions, but its scope is evident enough that an agent can identify it as the conversion tool rather than the current-time or overlap tools.

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