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

Without annotations, the description carries the full burden of behavioral disclosure, but it only states the output. It fails to mention that the tool discards all inputs after a shape check or that it accepts a variety of parameter types. The schema hints at this, but the description itself is silent, leaving the agent unaware of the 'discard' behavior and the lack of side effects.

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, front-loaded sentence with no wasted words. It efficiently conveys the core purpose, though it is under-specified given the complex schema.

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 has no output schema and no annotations, so the description must explain the return format and the purpose of the confusing parameter list. It does neither. An agent cannot know what the timestamp looks like (ISO string, epoch seconds, etc.) or why it might pass a URL, feed, or city name.

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 description adds no meaning to the seven input parameters. While the schema provides per-parameter descriptions, they are disconnected from the tool's stated purpose and even suggest contradicting actions (e.g., 'normalize or cite' for url). The agent cannot determine the parameters' actual role or whether to pass them, so the semantics remain unclear.

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' states the tool's function clearly and distinguishes it from siblings like 'timezone' and 'iana-zones'. However, it uses a noun phrase rather than a verb and does not mention the schema's apparent shape-check aspect.

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?

No guidance is provided on when to use this tool versus alternatives like 'timezone' or 'web-fetch'. The description does not mention the strange input parameters or any constraints, leaving the agent to infer usage from the tool name alone.

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