current_time

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

With no annotations, the description carries the full burden, and it discloses key behavior: it returns the current time in both the user's local timezone and UTC. It also adds context about the meaning of 'today' for the user. It does not specify the exact output format, but for a zero-parameter clock tool this is a minor gap.

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 short sentences, front-loaded with the core purpose ('Return the current time') and followed by a useful heuristic. No redundant wording; every sentence 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?

For a zero-parameter, no-output-schema tool, the description is complete: it states what is returned, the timezone scope, and provides practical guidance about 'today' for date filters. An agent has enough information to decide when and how to use this tool 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?

The input schema has zero parameters, so the baseline for this dimension is 4. The description cannot add parameter meaning because no parameters exist, and the 'Prefer `today`' note provides relevant usage context without being tied to any parameter.

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 states a specific verb and resource: 'Return the current time', and clarifies the exact output scope: user's local timezone and UTC. There is no ambiguity with sibling tools, which are all activity/person-oriented, so the tool is immediately distinguishable.

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 provides explicit guidance: use this tool for current time, but 'Prefer `today` for date filters' because it represents the user's local calendar date. This tells the agent when to use this tool versus relying on a more appropriate construct, going beyond merely naming the tool.

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