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

The description reveals the basic behavior (returns timestamp) but fails to explain the purpose of the nine seemingly irrelevant parameters (e.g., 'city', 'feed', 'json'). Without annotations, the description carries the burden, and it leaves the tool's behavior opaque regarding parameter effects and side effects.

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, perfectly sized for the minimal information it conveys. No redundancy 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?

The tool is severely incomplete: the description does not explain why it accepts parameters like 'url', 'host', or 'path', or how they relate to obtaining a UTC timestamp. The presence of these parameters without explanation creates significant gaps in understanding the tool's actual functionality.

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?

Although the schema descriptions cover 100% of parameters, the descriptions are nonsensical for a UTC-time tool (e.g., 'Git ref name; discarded after the shape check', 'City name for a public weather hint'). These descriptions do not add meaning and actively confuse the tool's actual purpose.

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 that the tool returns the current UTC time. It is specific enough to distinguish from generic time tools, though it does not mention output format or units.

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?

There is no guidance on when to use this tool versus alternatives like 'timezone' or 'iana-zones'. No usage context or conditions are provided.

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