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

With no annotations, the description carries the full burden, but 'Common IANA timezone names for clock calls' reveals no behavior. It does not mention output format, whether this is a static list, side effects, or that several inputs are discarded.

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 short phrase with no filler, but it is under-specified rather than concise. It lacks a verb and gives no structural guidance on how to invoke the tool.

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 no output schema, no annotations, and nine parameters, this description is incomplete. It does not explain what the tool returns, how the parameters relate to IANA zones, or that many parameters are discarded.

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 the baseline is 3; all parameters have their own descriptions. The tool description adds no parameter meaning, but the schema already documents each parameter.

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 identifies a resource (IANA timezone names) and a domain (clock calls), so it is not a tautology. However, it lacks an action verb like 'lists' or 'returns', and does not differentiate from sibling tools such as 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 phrase 'for clock calls' implies a timezone-related context, but there is no explicit guidance on when to use iana-zones versus timezone, utc-time, or other siblings. No alternatives or exclusions are provided.

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