time_now

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

No annotations are provided, so the description carries the burden; it is a read-only operation with no destructive concerns, which is straightforward. It discloses the return contents (ISO 8601, unix epoch, offset, DST, weekday, ISO week), which adds behavioral context, but this overlaps with the existing output schema and it says nothing about execution behavior beyond output.

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 tight sentences, front-loaded with the core purpose followed by the return detail. Almost every clause earns its place, with only minor redundancy against the output 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?

For a simple read-only time-lookup tool with an output schema already documenting return fields, the description covers the essential contract: what it returns and how timezones are specified. The only meaningful gap is the format parameter's exact syntax.

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%, so the description must compensate. It usefully explains the timezone parameter's accepted forms (IANA name, 'local', 'EST', '+03:30'), but the 'format' parameter is only alluded to via 'an optional strftime-formatted string' without naming it or its syntax, leaving half the parameters thin.

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: retrieving the current date/time in a given timezone. It clearly differs from siblings like time_convert, time_add, and time_difference, which perform transformations rather than reading the present moment. It does not name an explicit sibling, but the intent is unambiguous.

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?

Usage is implied (get the current time now) rather than stated. There is no explicit when-to-use versus alternatives guidance, nor mention of when-not to use it against siblings such as time_world_clock or time_format. Adequate but with clear gaps.

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