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

No annotations are provided, so the description must disclose behavioral traits. It does not mention that the parameters are mostly ignored, that the tool performs no side effects, or any edge cases. The description only states the output, leaving the agent unaware of how parameters like 'ref', 'url', or 'city' are handled (though schema hints they are discarded). This is a significant gap.

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 that essentially restates the tool name. It does not front-load any critical information beyond what the name implies, and the sentence does not earn its place by adding new value. It is concise but lacks substantive structure.

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 9 optional parameters, no output schema, and no annotations. The description provides no context about how the parameters affect the result, what the return format is, or any prerequisites. An agent would be left guessing whether passing parameters matters. This is grossly incomplete for the tool's complexity.

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 has 100% coverage with detailed descriptions for all 9 parameters, including notes like 'discarded after the shape check'. Per the calibration baseline, a score of 3 is appropriate when schema fully documents parameters and the description adds no extra semantic meaning. The description does not enrich parameter understanding.

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 returns the current UTC time. It is a specific, actionable statement, but it does not differentiate from sibling tools like 'timezone' which might also deal with time. Still, it is not a tautology since it adds the word 'current' and 'UTC'.

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 such as 'timezone'. No mention of scenarios where utc-time is preferred, nor any exclusions. The description is entirely silent on usage context.

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