now

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

No annotations are provided, so the description carries the full burden. It does disclose the return formats (ISO 8601, Unix timestamp, human-readable), but it does not explicitly state that the tool is read-only or free from side effects. For a simple 'now' tool, the implicit 'Get' suggests non-destructive behavior, but more direct disclosure would elevate the score.

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 precise and front-loaded: two sentences, no filler. Every word contributes to understanding the tool's purpose and output format. It is appropriately concise for the tool's simplicity.

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 tool's trivial nature (one optional parameter, no output schema), the description covers the essential aspects: what it does and what it returns. It does not describe the exact structure of the return value for multiple timezones, but this is not critical given the simple use case. The description is nearly complete for an agent to invoke it correctly.

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 coverage is 100% and the sole parameter 'timezones' is described in the schema. The description adds the notion of 'one or more' and gives examples, but this is marginal value over the schema's default documentation. The baseline score of 3 applies because the schema already carries the semantics.

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 uses the specific verb 'Get' and clearly states the resource as 'the current date and time', scoped to 'one or more timezones'. This distinguishes it from sibling tools like unix_timestamp, format_date, and date_diff, which focus on conversion or calculation rather than retrieval of the current instant.

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 clearly implies the tool is for retrieving current date/time across multiple timezones, which is a distinct use case among siblings. It does not explicitly state exclusions or alternatives, but the context is clear enough that an agent would know when to select it.

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