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

No annotations are present, so the description should disclose behavior itself. It doesn't specify the timestamp format (ISO string, Unix epoch), precision, or the fact that all seven schema parameters are irrelevant or discarded for this operation.

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 extremely terse and has no filler, with the key resource front-loaded. It earns a high score for conciseness, though it is potentially too brief for the complex seven-parameter schema.

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?

With no output schema and no annotations, the description must explain the return value and invocation constraints. It omits the output format and fails to clarify that the schema parameters are optional or ignored, leaving an agent uncertain about how to call the tool correctly.

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 already describes every parameter in detail, so a baseline of 3 applies. The description adds no parameter-level meaning and doesn't state that none of the parameters are needed, but the schema's own descriptions cover the disposal behavior.

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 clearly identifies the resource (current UTC timestamp) and conveys the operation is to produce that value. It doesn't use an explicit verb and doesn't differentiate from siblings like timezone or iana-zones, which is why it falls short of a 5.

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 about when to choose utc-time over the timezone-related siblings, nor any stated exclusions. An agent must rely on the tool name and common sense to select it.

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