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

No annotations are present, so the description carries the full burden. It states the core behavior (returning current UTC time) but completely ignores the seven input parameters listed in the schema, which are described as discarded after checks. The description does not disclose that these parameters are irrelevant or optional, creating potential confusion.

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?

A single, direct sentence that is front-loaded and without wasted words. It is efficient, though arguably too sparse given the complex schema it accompanies.

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 surprisingly rich input schema with detailed per-parameter descriptions, yet the one-line description does not explain why these parameters exist, whether they are optional, or how they relate to the timestamp output. Without output schema or annotations, an agent is left with significant ambiguity about the tool's actual behavior and expected inputs.

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 provides descriptions for all seven parameters, so coverage is 100%. The description adds no parameter information beyond what the schema already states. Baseline 3 applies because the schema does the heavy lifting.

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.' concisely identifies the tool's purpose and output, clearly distinguishing it from the sibling 'timezone' tool which handles time zones. It is a clear statement of what the tool provides, though it lacks an explicit verb.

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 other time-related tools. The description gives no context for selection, leaving the agent to infer usage from the name alone.

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