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

The description says nothing about behavior—no mention that inputs are largely discarded, that it performs a shape check, or what calling it returns. The schema's terse 'discarded after' notes hint at the behavior, but the description itself carries none of this burden, and no annotations were visible to fill the gap.

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 front-loaded seven-word sentence with no wasted wording. It earns its place, though the brevity comes at the cost of the detail penalized in other dimensions.

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 tool with a large, confusing parameter list and closely related siblings, one clause is insufficient. The description does not explain what a 'clock call' is, how the tool relates to timezone/utc-time, or what output an agent should expect, and there is no output schema to compensate.

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?

Each of the many schema parameters has at least a one-line description, so schema coverage is high and the baseline of 3 applies. However, the description adds nothing to clarify these parameters, and the parameter set (ref, url, city, feed, host, json, path) appears mismatched with a timezone-name tool, which the description does nothing to reconcile.

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?

"Common IANA timezone names for clock calls" conveys the resource domain (IANA timezone names) and hints at a supporting role for clock-related tools, which loosely distinguishes it from siblings like timezone and utc-time. However, it lacks an explicit verb (list? validate? return?) and does not state the deliverable, so the tool's exact function is left to inference.

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?

There is no guidance on when to use this tool versus siblings such as timezone, utc-time, or geo-hint. No alternatives, exclusions, or triggering conditions are mentioned, leaving the agent to guess whether this is a lookup, a validation, or a reference source.

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