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

With no annotations available, the description carries the full behavioral disclosure burden. It does not specify the timestamp format (ISO string, Unix epoch, etc.), whether the tool has side effects, or why the input schema contains seven unrelated-looking parameters such as `path` and `json` that are described as 'discarded' or checked without effect.

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 short sentence with no wasted words and the core capability is front-loaded. It could be slightly more informative without becoming verbose, but for such a simple tool the terseness is mostly appropriate.

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?

The tool has no output schema and no annotations, so the description must explain enough for an agent to invoke it correctly. It fails to specify what the returned timestamp looks like and does not clarify whether any of the seven optional-looking parameters are actually needed, leaving an agent confused about why a UTC-time tool accepts a file path, hostname, and JSON text.

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 input schema provides detailed descriptions for every parameter, including behavior such as 'discarded after the shape check' and 'no disk access', so schema coverage is high. The tool description itself adds no parameter-level meaning, but the schema already carries that burden.

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 what the tool returns: the current UTC timestamp. It is a specific resource and is distinguishable from the sibling `timezone` tool by the explicit 'UTC' qualifier, though it does not use a verb like 'get' and does not name any sibling explicitly.

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 implies usage when the caller needs the current UTC time, and the tool name reinforces this. However, it provides no explicit guidance about when to prefer this over related siblings like `timezone`, no exclusions, and no context about whether any of the many input parameters need to be supplied.

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