system_now

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

No annotations are supplied, but the description makes clear this is a pure lookup of the current instant in a named zone, so the read-only character is self-evident. It does not explicitly state that the call has no side effects, nor that the tz argument defaults to UTC when omitted, leaving the behavioral burden largely 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?

A single front-loaded sentence with the core noun phrase first and the format hint in parentheses. Nothing is wasted and nothing is buried.

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 one-optional-parameter read tool with an output schema, the description covers what the tool returns and how to format the argument. The only omission is stating that omitting tz yields UTC, which the schema's default already implies.

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 0% - the schema only names the parameter 'tz' as a string with a default. The description compensates by specifying the IANA identifier format and giving two valid examples, which is exactly the meaning an agent needs to fill the field correctly.

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 resource precisely: the current date/time resolved for a given IANA timezone, with concrete examples. It does not differentiate itself from the sibling automation_timestamp, so an agent must infer which clock tool to pick.

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?

There is no explicit when-to-use or when-not-to-use guidance, and no sibling (notably automation_timestamp) is named as an alternative. The only implied guidance is that the caller may pick a timezone.

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