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

With no annotations, the description must disclose behavior. It only states the output (timestamp) but does not mention side effects, error conditions, or that all parameters are discarded after shape checks. The description is grossly insufficient for a tool with this complexity.

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, but conciseness is not the same as under-specification. It is a single sentence with no structure or prioritization. It is short but lacks necessary content to guide the agent.

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 tool with 9 parameters, no output schema, and no annotations, this description is completely inadequate. An agent cannot determine what inputs are relevant, what the output format is, or how to use 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%, but the description adds no value about how parameters relate to the tool's purpose. The schema describes each parameter, but the tool description gives no hint why a UTC time tool accepts a city or a URL. The agent cannot understand the intended usage from the description.

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 returns the current UTC time. It identifies the resource (UTC timestamp) and implies the action (get). However, it does not differentiate from sibling tools like 'timezone' or 'iana-zones', so it loses a point.

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?

There is no guidance on when to use this tool versus alternatives. The description is a single sentence with no context about preferred use cases or when a sibling tool would be more appropriate.

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