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

With no annotations present, the description carries the full burden of behavioral disclosure, and it only states the bare output. It does not reveal the timestamp format, precision (e.g., seconds vs milliseconds), whether the four input parameters are ignored, or any other behavioral traits. This is adequate only for the most trivial interpretation.

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 only four words, making it extremely concise and front-loaded. However, this brevity crosses into under-specification: it saves words at the expense of necessary guidance, so it does not fully earn its place as an adequate description.

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 four parameters, no annotations, and no output schema, yet the description explains none of them. It fails to clarify why url, host, json, and zone appear in the schema for a UTC time tool, what the returned value looks like, or how it differs from timezone-related siblings. For a tool with this schema complexity, the description is incomplete.

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 each of the four parameters (url, host, json, zone) already has its own schema description, meeting the baseline. However, the description adds no information about how these parameters relate to getting a UTC timestamp, and the parameters appear semantically mismatched with the tool's stated 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" essentially restates the tool name 'utc-time', adding only the words 'current' and 'timestamp'. It implies a read operation returning the present UTC time, but there is no explicit verb or resource elaboration, making it a tautology rather than a clear functional definition.

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?

No guidance is provided on when to use this tool versus the sibling tools timezone or tz-australia-sydney, which are closely related. The description offers no context for selection, no exclusions, and no mention of alternatives.

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