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

With no annotations and only the phrase 'Current UTC timestamp', the description does not disclose that all input parameters are apparently ignored or discarded (as hinted by property descriptions like 'discarded after the shape check'). It also does not state whether the operation is pure or has side effects, leaving behavioral assumptions to the agent.

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 with no unnecessary words or repetition. It is well-structured and easy to parse.

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 a complex and confusing schema with nine optional parameters, but the description does not clarify their relevance or indicate that they are ignored. It also does not specify the return format of the timestamp (e.g., ISO 8601, epoch), leaving important context missing for an agent to use it correctly.

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 has 100% coverage with each parameter described individually, many noting they are discarded or not used. However, the tool description itself does not explain why these parameters exist for a UTC timestamp tool, so the descriptions do not integrate meaningfully with the intended purpose. The baseline of 3 is appropriate due to high schema coverage.

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 indicates the primary function, but the input schema includes many unrelated optional parameters (e.g., 'ref', 'url', 'city') that obscure the purpose and suggest the tool may do more. It is not as clear as a simple 'Get the current UTC time' with an empty schema.

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 explicit guidance on when to use this tool versus sibling tools like 'timezone' or 'iana-zones'. The description implies it is for getting a UTC timestamp, but it does not mention alternatives, exclusions, or when not to use it.

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