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

With no annotations provided, the description carries the full burden of disclosing behavior, but it only describes content ('Common IANA timezone names'), not what happens when the tool is invoked. It does not mention whether this is a read-only lookup, whether results are returned, or that the passed values are reportedly discarded, leaving the tool's behavior opaque.

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 text is short and free of filler, but it is a fragment rather than a sentence with a verb, and it omits essential operational context. This is under-specification rather than effective conciseness.

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?

Given 9 optional parameters, no annotations, and no output schema, the description is far too sparse. It does not explain return values, side effects, how parameters relate to the tool's purpose, or how this tool should be invoked relative to the many sibling shape/time tools.

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?

Although the schema descriptions cover 100% of parameters, the tool description points to IANA timezone names while the schema contains unrelated parameters such as ref, url, city, feed, host, json, and path—with no timezone parameter at all. This mismatch actively confuses rather than helps an agent map the description to the 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 operation verb, so it does not state what the tool does—returns, lists, validates, or stores. It mostly restates the tool name ('iana-zones') and, alongside siblings like 'timezone' and 'utc-time', does not clearly distinguish itself.

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?

It gives a vague purpose ('for clock calls') that implies use when working with clock/timezone tools, but it never explicitly says when to use this tool versus alternatives such as 'timezone' or 'utc-time'. No exclusions, prerequisites, or alternative routing are provided.

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