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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the output format (ISO 8601, UTC) and that it returns the current time, but it does not explicitly mention that the operation is read-only, has no side effects, or any other behavioral traits. For a trivial time-retrieval tool this is adequate, but it adds no extra context beyond the obvious purpose.

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 a single sentence with zero waste, front-loading the primary purpose and key details (ISO 8601, UTC). Every word earns its place, and the structure is optimally efficient.

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?

For a tool with no parameters, no output schema, and no annotations, the description fully specifies what the tool returns (current server time) and in what format (ISO 8601, UTC). Nothing an agent needs to call or interpret the result is missing.

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 schema provides no parameter documentation. The description compensates by specifying the return format and timezone, which is relevant context even though it is not about parameter semantics. Per the calibration baseline for 0 parameters, a score of 4 is appropriate.

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 a specific verb ('Returns'), resource ('current server time'), and format constraints (ISO 8601, UTC), which clearly differentiates it from the sibling tools 'add' and 'echo'. An agent can immediately understand what this tool does without ambiguity.

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 description provides no explicit guidance on when to use this tool versus alternatives, though the siblings are obviously unrelated operations. Usage is implied by the tool's purpose, but the description does not state conditions or exclusions, so it only meets the 'implied usage' level.

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