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

With no annotations provided, the description carries the full behavioral burden. It discloses the output format (ISO 8601) and timezone (UTC), which are the key behavioral details for a zero-parameter read-only tool. It does not mention potential caveats like precision or network dependency, but none are expected for this simple 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?

A single, front-loaded sentence conveys everything needed. There is zero wasted text, and the key facts (server time, ISO 8601, UTC) are stated directly.

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 is minimal: no parameters, no output schema, no annotations. The description fully specifies what an agent needs to know—what it returns and in what format—leaving no missing information for correct invocation.

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 tool has zero parameters, so the baseline is 4. The description correctly adds no parameter information since there is none to document.

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 uses a specific verb ('Returns'), a resource ('current server time'), and specifies the exact format ('ISO 8601, UTC'). This makes it immediately distinguishable from siblings 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?

The context is clear: the tool is for retrieving the current server time. No exclusions or alternative conditions are needed since the siblings are unrelated operations. It could explicitly state 'use when you need server time,' but the purpose is unambiguous.

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