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 clearly states bidirectional conversion and the API-bridging purpose, but it omits details about timezone handling and the exact output structure for 'epoch values', leaving minor ambiguity.

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 front-loaded with a concise, specific first sentence, followed by well-organized 'Use when' and 'Do not use when' lists. No sentence is wasted; all content contributes to tool selection and correct invocation.

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 simple two-parameter converter with complete schema coverage, the description adequately covers purpose, usage, and exclusions. However, since no output schema is present, the description could more precisely specify the output format for 'epoch values', preventing a perfect score.

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 already documents both parameters with 100% coverage, so a baseline of 3 is appropriate. The description adds useful context about bridging API time formats but does not provide additional parameter-level details beyond what the schema already states.

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 opens with a specific conversion statement ('Convert Unix epoch seconds or milliseconds to ISO-8601, or an ISO-8601 datetime to Unix epoch values'), making the tool's function unambiguous. It also distinguishes from sibling tools via explicit 'Do not use when' examples such as timezone_convert and unit_convert.

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 'Use when' and 'Do not use when' sections, including named alternative tools. This gives the agent clear, actionable criteria for choosing this tool over its siblings.

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