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

With no annotations, the description must disclose behavior, but it only offers a noun phrase. It doesn't indicate whether the tool is read-only, whether it accesses external data, whether it has side effects, or what the output format is. The phrase 'for clock calls' hints at a purpose but says nothing about the actual operation.

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 extremely short—a single phrase. While brevity is valued, here it is under-specification rather than conciseness. There is no structure, and the sentence doesn't front-load any actionable information. It fails to earn its place because it conveys almost no usable guidance.

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?

The tool has 9 parameters, no output schema, and no annotations. The description gives no indication of what the tool does, what it returns, or how the parameters are used. It is completely inadequate for an agent to safely and correctly invoke this tool, even for a simple lookup.

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?

The schema covers all 9 parameters with individual descriptions, so the baseline is 3. However, the tool description adds no context about how the parameters relate to the tool's purpose. For instance, 'ref' is described as discarded, but there's no explanation of why it exists. Since none of the parameters are required and the description doesn't clarify which are relevant, the value added is minimal.

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 states it provides common IANA timezone names for clock calls, but it doesn't specify what the tool actually does with those names—whether it returns a list, validates a zone, or resolves a timezone from a given input. The verb is missing; 'for clock calls' is ambiguous and doesn't distinguish it from sibling tools like 'timezone' or 'utc-time'.

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?

No guidance is given for when to use this tool versus alternatives. There is no mention of conditions, prerequisites, or exclusions, and none of the sibling tools are referenced. An agent would have no way to know if this is the right tool for a task.

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