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

No annotations existed. The description says only what the tool returns. It provides no behavioral details about side effects or discards of parameters, but the input schema descriptions already state that parameters are discarded after checks. The description itself does not disclose the side effect of not using parts of the schema, so it partially relies on the schema.

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, short sentence with one key fact. It is not verbose and is front-loaded. It is appropriately minimal for the simplicity of the core behavior, though it could have added a note about the ignored parameters.

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 core behavior (return current UTC timestamp) is fully stated, but the schema contains nine optional parameters that all carry a 'discarded' note, and the description does not clarify that these parameters are irrelevant. An agent may wonder if calling with a URL or JSON affects the time. A fuller explanation such as 'any provided arguments are ignored' would increase completeness.

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?

Schema description coverage is 100%, and each parameter description explains that they are discarded after shape or other checks. The tool description adds no information about parameters. Therefore the baseline score of 3 is appropriate, as 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 states the tool returns the current UTC timestamp, which is only a generic action, and the resource is a timestamp. It is not a tautology and distinguishes it from other time-related tools implicitly, but it does not explicitly compare with siblings like timezone or iana-zones.

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 gives the implied use case: when the current UTC timestamp is needed. It does not state alternatives such as timezone for a specific timezone or mention exclusions. No explicit when-not statements are present.

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