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

With no annotations provided, the description carries the full burden of behavioral disclosure. It clearly states the operation is a read (returns a value) and specifies the format and timezone, giving an agent enough confidence to invoke it without side-effect concerns. It omits details like clock accuracy or caching, but for a zero-parameter utility this is sufficient.

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, focused sentence that delivers the essential information (action, resource, format, timezone) without any filler. The key qualifiers (UTС) are included, and the sentence is front-loaded with the primary purpose.

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?

Given the tool has no parameters, no output schema, and no annotations, the description fully covers what an agent needs to know: what it returns, in what format, and from where. There is no missing behavioral or usage context.

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?

There are zero parameters, so the schema is the structured baseline. The description adds no parameter details, but none are needed; per the rubric, a zero-parameter tool gets a baseline of 4 when schema coverage is perfect, which it is.

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 states the specific action 'Returns' a particular resource: the current server time, with format (ISO 8601) and timezone (UTC). This is unambiguous and clearly distinguishes it from sibling tools like 'add' and 'echo'.

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?

While it does not explicitly mention alternatives or exclusions, the description makes it obvious when to use the tool: whenever the current server time is needed. No other sibling relates to time, so the context is clear without more guidance.

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