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 mentions 'multiple reliable sources' hinting at redundancy or failover, but does not disclose potential latency, error handling, authentication requirements, or the structure of the response. It doesn't state whether the operation is read-only (though 'get' implies it) or any side effects. Given the lack of annotations, this is a significant gap in transparency.

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 that is front-loaded with the core action ('Get accurate UTC time') and includes only necessary detail. There is no fluff or redundant information, making it highly efficient for an agent to parse.

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 tool is simple with one optional parameter and no output schema. The description clearly states what it does, but it does not describe the return value structure or any error conditions. An agent might not know if the response is a formatted string, object, or something else. While the format parameter implies the output format, the lack of specification about the response shape leaves a completeness gap.

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 schema description coverage is 100% – the 'format' parameter is fully described with its enum values and default. The description adds no additional meaning about the parameter beyond what the schema already provides. Therefore, the baseline score of 3 is appropriate, as the schema does the heavy lifting and the description adds no extra value.

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 uses a specific verb ('Get') and a clear resource ('accurate UTC time'), and adds 'from multiple reliable sources' which clarifies the purpose and distinguishes it from any potential simple time lookups. Since there are no sibling tools to differentiate, this is unambiguous and immediately understandable.

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 clearly implies the tool is for retrieving UTC time accurately, which sets the context for when to use it. With no sibling tools, there are no alternative comparisons needed, but it does not explicitly state exclusions or when not to use it. However, the purpose is explicit enough that an agent can infer the intended usage, so it earns a 4.

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