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

Aside from stating the output, the description does not disclose side effects, network usage, or how the many optional parameters affect behavior. Some parameter descriptions mention being discarded, but the tool description itself does not clarify whether all 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 a single, concise sentence that immediately states the tool's purpose. There is no extraneous information or unnecessary detail.

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 output schema and no annotations, the description should have specified the return format (e.g., ISO 8601) and clarified how the optional parameters are handled. It only says 'Current UTC timestamp,' leaving important contextual details unstated.

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 schema descriptions cover all 9 parameters and explicitly state that several are discarded or used only for validation. However, the tool description itself adds no parameter-level meaning beyond the schema, so the baseline of 3 is appropriate.

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 clearly states the tool's core output—a current UTC timestamp—which is enough to understand its primary purpose. It is short but unambiguous, and the tool name reinforces this meaning.

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 description provides no guidance on when to use this tool, when not to use it, or how it relates to sibling time-related tools such as timezone or iana-zones. An agent would have to infer appropriate usage from the name alone.

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