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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds only 'Returns delta hours and current local times,' which is redundant with the existing output schema, and the trailing 'voyage calculators' pointer is unexplained rather than informative.

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?

Front-loaded with the verb and mostly tight, but the closing sentence ('See list_bundles for related voyage calculators') is tangential noise for a timezone tool and does not help invocation. Four short sentences, one of which does not earn its place.

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?

Annotations and an output schema are present, so much of the burden is carried elsewhere. Still, for a tool sitting among many look-alike time calculators, the description omits the disambiguation an agent most needs, leaving the definition minimally viable.

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% and both parameters are enums of explicit city values, so the schema already carries the semantics; baseline 3 applies. The description's 'Inputs: timezone A, timezone B' actually conflicts slightly with the schema's city-based parameters, adding no real meaning.

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 and resource: 'Compute the time difference (hours) between two timezones.' That is clear enough for an agent to understand the operation. However, it does nothing to distinguish itself from the many near-duplicate siblings (calculate_time_difference, calculate_timezone_convert, calculate_timezone_offset, convert_time), and it describes inputs as 'timezones' while the schema actually takes city names.

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?

'Use for international meetings' gives one implied scenario but no conditions for choosing this tool over the overlapping time/timezone siblings. There are no exclusions or named alternatives, which matters a lot given ~8 time-related calculators in the sibling list.

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