now

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

No annotations are present, so the description carries the full burden. It discloses timezone (UTC) and format (ISO-8601), and 'current' implies a stateless read. It does not mention precision, potential latency, or response structure, but for a trivial time tool this is adequate.

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 no filler. Every word earns its place.

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?

Complexity is minimal, an output schema exists, and the description covers the essential behavior. It lacks explicit alternative routing, but that is not material for a zero-parameter UTC clock.

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?

There are zero parameters, so there is nothing to document. Schema coverage is complete and the description's format note adds useful context beyond the empty input schema.

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 exactly what the tool returns (current UTC time) and the format (ISO-8601). It is clearly distinct from sibling tools like calc, json_get, or read_file, which operate on different resources.

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 context is clear: call when a current UTC timestamp is needed. It does not explicitly name alternatives or exclusions, but with zero parameters and a dedicated time resource, the usage is self-evident and no sibling competes.

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