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

With no annotations, the description carries the full burden, but it only states what the tool is for, not what it does with inputs, what it returns, or whether it has side effects. The parameter descriptions hint at 'discarded' values, but the main description does not disclose behavior.

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 front-loaded, with no redundant prose. It loses points only because the extreme brevity omits necessary details, not because of wasted words.

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?

Despite a 9-parameter schema and no output schema, the description gives almost no context about expected inputs, output, or relation to sibling tools. The confusing parameter descriptions are not resolved, leaving an agent unable to confidently invoke the tool.

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 input schema includes nine optional strings, most of which (ref, url, city, feed, host, json, path, query) are unrelated to IANA timezone names and have confusing descriptions like 'discarded after the shape check.' Only 'zone' is clearly relevant, so the description adds little and largely obscures how the tool should be called.

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 the resource as 'common IANA timezone names for clock calls,' which is reasonably specific and distinct from sibling time tools. However, it is phrased as a noun phrase rather than an action (e.g., 'list'), and the name alone doesn't clarify whether this returns a list or checks a name.

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 about when to use this tool versus the many sibling tools like timezone, tz-asia-bahrain, or utc-time. There are no conditions or examples to help an agent select it.

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