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

With no annotations provided, the description carries the full burden of behavioral disclosure. It only states the output (UTC timestamp) but does not disclose that it accepts 9 optional parameters that are used for 'shape checks' and then discarded, as implied by the schema. The tool likely performs validation on the parameters, but the description does not mention this side effect or the fact that parameters are ignored in terms of output. This is a significant 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?

The description is a single, concise sentence with no wasted words. It is front-loaded with the core purpose. However, given the tool's complex schema with 9 parameters, the brevity borders on under-specification, but conciseness itself is well executed.

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 incomplete for a tool with 9 parameters and no annotations. It does not explain why the parameters are present, whether they are required, or how they affect the call (even though they are all optional and discarded). An agent would be uncertain whether to supply any of these parameters or what the tool does with them. There is no output schema, and the description's one line does not address the operational complexity.

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 100%, so the schema already provides detailed meaning for each parameter (e.g., 'Git ref name; discarded after the shape check'). The description adds no parameter-related information beyond stating the output. According to the baseline for high schema coverage, a score of 3 is appropriate even without additional description content.

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 clearly states the tool's function: returning the current UTC timestamp. It is a specific verb and resource, making the purpose unambiguous. However, it does not differentiate from sibling tools like 'timezone' or 'iana-zones', which could also provide time-related data, so it lacks sibling differentiation.

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 provides no context about scenarios where this tool is preferred, nor does it mention any exclusions or alternatives. An agent cannot determine whether to use 'utc-time' or 'timezone' based on this description alone.

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