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

There are no annotations, and the description does not disclose whether the operation is read-only, has side effects, requires permissions, or what the output format looks like. The tool's behavior beyond returning a timestamp is entirely 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 description is a single sentence with no unnecessary words, making it highly concise. However, it omits critical details, but that is a matter of completeness rather than conciseness; the structure is efficient.

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 tool, the description fails to provide essential context: it does not specify the timestamp format (e.g., ISO 8601), how the parameters relate to the operation, or what the response contains. The confusing parameter descriptions exacerbate the incompleteness, leaving the tool's usage ambiguous.

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 includes 9 optional parameters, but their descriptions are nonsensical and unrelated to UTC time (e.g., 'Git ref name; discarded after the shape check', 'Search text; discarded after the length check'). These add no meaningful information and actively mislead, providing no value over the bare 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 'Current UTC timestamp.' clearly states the tool's purpose: it returns the current UTC time. This is specific and distinguishes it from sibling tools like 'timezone' or 'iana-zones', though it lacks elaboration on the exact format or additional details.

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 on when to use this tool versus alternatives such as 'timezone' for timezone conversions or 'iana-zones' for zone lists. The description gives no context for selecting this tool among its siblings.

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