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

With no annotations provided, the description alone carries the burden of disclosing behavior. It states the operation is a conversion, implying a pure transformation with no side effects. However, it does not explain supported units, rounding behavior, invalid input handling, or the output format, leaving a meaningful gap in behavioral 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, compact sentence with no redundant phrasing. The 'Weight:' prefix is helpful as a title, and every word contributes to the meaning. It is appropriately sized for the simplicity of the tool and is easy to parse quickly.

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?

Despite the simple purpose, the description is incomplete for correct invocation. It does not list accepted units (e.g., kg, lb), whether the value string must be numeric, or what the response looks like. The input schema descriptions are effectively meaningless, so with no output schema and no annotations, the agent cannot confidently call the tool without guessing.

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%, so the baseline is 3. The description clarifies that 'from' and 'to' represent weight units and 'value' is the quantity to convert, which adds meaning beyond the unhelpful schema descriptions like 'To to process.' However, it does not specify valid unit names or the expected format of 'value,' so the added semantic value is limited.

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 states a specific verb and resource: 'Convert between weight units.' This clearly identifies what the tool does and inherently differentiates it from sibling unit converters like x402-temperature and x402-length. It avoids pure tautology by adding the conversion action, so an agent can recognize its purpose immediately.

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 implies the tool should be used when a weight unit conversion is needed, which is a clear contextual signal. However, there is no explicit guidance about when not to use it, nor any mention of alternatives such as the generic x402-units-convert sibling. No exclusions or comparison are provided.

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