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

With no annotations provided, the description bears full responsibility for disclosing behavior, but it reveals nothing about side effects, return values, data handling, or output format. The only hint is 'for clock calls,' which is too vague to count as meaningful behavioral context.

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, but this is under-specification rather than effective conciseness. It is a fragmented phrase that omits critical details, and while it is front-loaded, there is no structure or substance to evaluate.

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 seven parameters, no annotations, and no output schema. The description provides almost no information to help an agent select or invoke the tool correctly. It fails to explain the parameters, expected inputs, return value, or relationship to sibling tools like timezone or utc-time.

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 does not explain any of the seven parameters, and the schema's parameter descriptions (ref, url, city, feed, host, json, path) appear completely unrelated to IANA timezone names. The schema descriptions are present but irrelevant to the tool's stated purpose, and the description fails to bridge the gap.

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 verb or action. It doesn't state whether the tool returns, validates, or lists these names. It vaguely references 'clock calls' but doesn't specify what the tool does with the names, leaving the agent to guess.

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 alternatives. The sibling list includes timezone and utc-time, both potentially related, but the description offers no comparison, conditions, or exclusions. An agent cannot determine when iana-zones is the appropriate choice.

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