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

With no annotations present, the description carries the burden of explaining behavior. It conveys the core read-only behavior of returning the current time, but it does not disclose output format, invalid-zone handling, or that most schema parameters are ignored.

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 eight words and front-loaded with the core action and object. Every word is functional, with no filler or repetition.

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 simple time lookup, the description plus the schema is minimally sufficient: the schema identifies the relevant zone parameter and describes the other parameters as discarded. However, the description alone does not clarify which parameter to use, and there is no differentiation from closely related sibling 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?

Schema coverage is 100%, so the baseline is 3. The description's 'IANA timezone' wording adds a small clarification, but the schema already describes the zone parameter as 'IANA timezone name to look up,' so the description adds little beyond the schema.

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 uses a specific verb and resource: 'Current time in a named IANA timezone.' It clearly states what the tool does, but it does not explicitly differentiate it from sibling tools like utc-time or iana-zones.

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 provided about when to use this tool versus alternatives such as utc-time or iana-zones. The description only states the tool's function, leaving selection to inference.

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