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

No annotations are present, so the description must fully disclose behavior, but it does not. It never states what the tool returns, whether there are side effects, or how 'common' zones are determined. The schema's unrelated-looking parameters with 'discarded' descriptions only deepen the opacity.

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 single sentence is concise, but it is under-specification for a tool with nine parameters and no annotations. There is no front-loaded operational summary; the text reads more like a label than a functional description.

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?

With no annotations, no output schema, nine parameters, and a large set of siblings, this description is far too thin for an agent to invoke the tool correctly. It lacks return format, selection criteria, and any explanation of the parameter payload. The tool cannot be safely chosen or called based on this definition alone.

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 even though the tool description mentions no parameters. The schema already explains each parameter, but the description does not connect any of them to the stated IANA timezone purpose. This is acceptable but adds no extra parameter meaning.

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') rather than a statement of what the tool does. It adds only the qualifiers 'common' and 'for clock calls' but does not specify whether the tool lists, validates, or returns these names. Sibling tools like 'timezone' and 'utc-time' are not differentiated.

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' gives a weak hint of context, but there is no explicit guidance on when to use this tool versus alternatives such as 'timezone' or 'utc-time'. No exclusions, prerequisites, or alternative routing are provided, so an agent cannot reliably select it.

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