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

With no annotations to rely on, the description carries the full burden of behavioral disclosure and reveals nothing beyond a vague domain reference. It does not state why call output is, whether parameters are needed, or whether the function has side effects or constraints.

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 short and free of fluff, but it is under-specified to the point of being unhelpful. A single vague phrase does not earn full credit for conciseness because it omits essential semantic content.

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 no output schema and the description does not explain what the tool returns, how to invoke it, or why the listed parameters exist. It is incomplete even for a simple helper tool, as there is no actionable context for an agent.

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 description adds no parameter-level meaning, but the schema already describes all seven properties in detail, including notes like 'discarded after the shape check'. With high schema coverage, the baseline of 3 is appropriate even though the description itself is silent about parameters.

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 is a noun phrase ('Common IANA timezone names for clock calls') with no explicit verb or action, so it does not clearly state what the tool does or returns. The name 'iana-zones' nearly repeats the description, and it does not distinguish the tool from siblings 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?

The description provides no explicit guidance on when to use this tool versus alternatives. The phrase 'for clock calls' weakly implies a relationship to clock-related tools, but there is no integration.

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