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

No annotations are provided, so the description carries the full burden. It usefully discloses the no-authentication/no-cost profile, which matters for tool selection, but says nothing about output shape, rounding, error behavior for unsupported unit pairs, or case sensitivity.

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?

A single sentence with the key qualifier (free, no key) front-loaded and the supported domains compactly enumerated. No waste.

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 three-required-parameter conversion tool with no output schema, the description covers scope and access constraints adequately. Minor gaps remain around accepted unit string formats and how ambiguous inputs (e.g. case, temperature scales) are handled.

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 67%; 'from' carries examples ('mi, kg, f, gib') while 'to' is only labeled 'unit'. The description's category list adds useful indirect guidance about which unit strings are valid, but does not clarify the asymmetry between 'from' and 'to' or value formatting.

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?

States a specific verb ('Convert') and resource ('units') and enumerates the supported domains, which clearly separates it from arithmetic or finance siblings. The parenthetical exclusion of currencies further sharpens the scope.

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?

'FREE, no key' establishes context for when the tool is usable, and '(no currencies)' implicitly steers currency questions elsewhere (e.g. the forex-related siblings), but no alternative is named and there is no explicit when-not-to-use guidance beyond the currency note.

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