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

With no annotations provided, the description carries the disclosure burden and does so well on the return side: it enumerates Unix seconds/milliseconds, ISO 8601 in both UTC and the requested zone, weekday, ISO week, and day of year. It omits that the call is side-effect free and needs no auth, but for a pure clock read that gap is minor rather than risky.

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?

Two sentences, front-loaded with the purpose before the return payload. Every clause earns its place: the return-field enumeration is the most useful part and it is not padded with filler.

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?

There is no output schema, so the description must explain return values, and it does so concretely for every field the caller would otherwise have to discover empirically. Combined with the schema's documented default of UTC, an agent has everything needed to call and consume the result.

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 the single timezone parameter is fully documented in the schema with an example and its UTC default, so the description need only confirm it. It does reference "the requested IANA time zone," but adds no syntax or format detail beyond the schema, which is the expected baseline.

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?

States a specific verb+resource ("Get the exact current date and time") that is immediately distinguishable from siblings like date_calc, convert_timestamp, and date_calc, which manipulate rather than report time. Nothing about the intent is ambiguous.

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 parenthetical "(you cannot know it otherwise)" implicitly directs the agent to call this rather than guess the time, which is a real usage signal. However, it names no alternatives and gives no when-not guidance, even though convert_timestamp and date_calc sit adjacent in the sibling list and could plausibly be confused with it.

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