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

With no annotations provided, the description must disclose behavior, but it only states the output. It fails to mention that all input parameters are unrelated to the timestamp and are discarded or validated, leaving the agent unaware of the tool's actual handling of arguments beyond the empty call.

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 concise and front-loaded, with no wasted words. However, it is so terse that it omits crucial context about the parameter list, so the conciseness is not fully appropriate given the schema complexity.

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 unexpected array of parameters with varied descriptions (e.g., 'normalize or cite', 'discarded after shape check'), the description is incomplete. An agent cannot understand why the tool accepts these unrelated inputs or whether they change the behavior, making the definition inadequate for correct invocation beyond a no-argument call.

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?

While the schema descriptions for each parameter are detailed, the tool description 'Current UTC timestamp.' does not explain how these parameters relate to the tool's function. It is unclear whether they are required, optional, or strictly ignored, creating confusion for an agent deciding what to pass.

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 'Current UTC timestamp.' clearly identifies the tool's primary function: returning the current UTC time. It is unambiguous and distinguishes it from timezone-related siblings like 'timezone', but it lacks an explicit verb and does not account for the numerous input parameters in the schema.

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 guidance on when to use this tool versus alternatives like 'timezone' or 'iana-zones'. It does not state whether parameters should be supplied, ignore alternative time sources, or any other selection criteria.

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