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

With no annotations, the description carries the behavioral disclosure burden. It states the core behavior (returns current time for a named timezone) but does not disclose error handling, edge cases (e.g., invalid IANA names), or what happens with the many other input parameters. The schema descriptions partially compensate by noting that other fields are 'discarded', so the description adds minimal extra value beyond the schema.

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 a single, punchy sentence with no filler. The core purpose is front-loaded and immediately actionable. Efficiency is high.

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?

Despite the simple purpose, the tool has 9 input parameters, and the description gives no hint about which one to use. The output schema is absent, and there is no comparison to utilities like utc-time. An agent would need to read the schema carefully to avoid calling with extraneous parameters, making the description insufficient for correct invocation.

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 is already explained in the schema. The description does not mention the 'zone' parameter or clarify which of the 9 parameters is relevant, but the schema provides sufficient detail, yielding a baseline of 3.

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 "Current time in a named IANA timezone" clearly specifies the verb (get current time) and resource (named IANA timezone). It distinguishes this tool from siblings like utc-time (which gives UTC) and iana-zones (which lists zones) without ambiguity.

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 provides no guidance on when to use this tool versus alternatives such as utc-time or iana-zones. An agent is left to infer usage from the tool name and the schema, with no explicit criteria for selection or exclusions.

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