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, but it only states the output value. It does not describe the timestamp format, whether parameters affect the result, or any side effects. The tool appears read-only, but nothing explicitly confirms this.

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 short and front-loaded, but it is a bare noun phrase rather than a structured explanation. It is concise, yet for a tool exposing seven input parameters, the one-sentence description omits too much context to be considered well-structured.

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 no output schema, so the description should clarify return format, but it does not. It also fails to explain why the tool accepts seven unrelated input parameters when its sole purpose appears to be returning a current UTC timestamp.

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 documents all seven parameters with descriptions, so schema coverage is high and the baseline is 3. The description itself adds no parameter semantics, but the schema already explains that values like 'ref' are 'discarded' and 'path' involves 'no disk access'.

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.' is essentially a restatement of the tool name 'utc-time', adding only the word 'current'. It lacks a verb and does not distinguish this tool from the sibling 'timezone', so the agent gets no clearer signal than the name itself.

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 'web-fetch'. The description gives no context for scenarios where UTC time is needed, and no mention of when it should not be used.

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