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

With no annotations provided, the description carries the full burden of disclosing behavior. It merely states the result (a timestamp) but does not mention that most parameters are discarded, that the tool performs validation (per the schema descriptions), or any side effects or return details. This is a significant gap for a tool with such a complex schema.

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, but it is under-specification rather than conciseness. It fails to convey the tool's actual function, which involves handling multiple parameters. The brevity does not earn its place because it omits critical information.

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 tool with nine optional parameters, no required fields, and no output schema, this description is grossly incomplete. It does not explain what the tool does with the parameters, what it returns, or how it relates to the sibling tools. An agent cannot correctly invoke this tool based on this description alone.

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?

Schema description coverage is 100%, so all parameters have explicit descriptions in the schema. The tool description adds nothing about parameters, but per the rubric, the baseline is 3 when coverage is high. However, the parameter descriptions themselves hint at the tool's true nature (e.g., 'discarded after the shape check'), which is not reinforced in the description.

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.' simply restates the tool name 'utc-time' without adding any operational detail. It fails to explain why the input schema contains nine unrelated parameters such as 'ref', 'url', 'city', and 'json', leaving the actual purpose ambiguous. This is a tautology, not a functional explanation.

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'. The description offers no context, exclusions, or selection criteria, leaving an agent to guess the appropriate scenario for invocation.

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