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

The description offers no information about side effects, dependencies, or idempotency. More critically, the parameter descriptions (e.g., 'Git ref name', 'HTTPS URL', 'City name') are misleading and imply functionality unrelated to a timestamp, which could cause an agent to pass irrelevant arguments. Without annotations, the tool's behavior is opaque and potentially deceptive.

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 extremely concise, consisting of a single phrase with no unnecessary verbiage. It is well-structured for brevity, but lacks any additional structural elements like examples or notes. Given the tool's simplicity, this level of conciseness is appropriate, though it does not compensate for missing information elsewhere.

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?

The description is grossly incomplete for the tool's context. It does not specify the return format (e.g., ISO 8601, milliseconds), whether it returns just the time or includes a date, or how the parameters relate to the operation. The presence of nine parameters with unrelated descriptions and no output schema leaves the agent without essential information to invoke the 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?

All nine parameters have descriptions that are nonsensical for a UTC timestamp tool (e.g., ref, url, city, feed). The schema coverage is 100%, but the descriptions are entirely irrelevant and do not clarify that these parameters might be ignored or accepted for compatibility. The tool description itself does not mention any parameters, leaving the agent with no way to understand why they exist or how to use them.

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 'Current UTC timestamp' clearly states the tool's core function of returning the current UTC time. It is a concise verb-noun phrase that distinguishes it from sibling tools like timezone or iana-zones, although it lacks specifics about the format or source.

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?

No guidance is provided on when to use this tool versus alternatives. Sibling tools like timezone or iana-zones exist, but the description gives no indication of when a user should prefer this one, leaving the agent to guess based on the tool name alone.

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