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

No annotations are provided, so the description carries the full behavioral burden. It says nothing about the conversion factor, which ton definition is used (metric/short/long), rounding behavior, precision, or accepted input formats. For a conversion tool with zero annotation coverage, these are exactly the details an agent needs and they are absent.

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, front-loaded sentence with zero waste — the purpose is stated immediately. It is appropriately sized for a one-parameter conversion tool. Slightly terse, but conciseness is a virtue here rather than a flaw.

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?

No output schema, no annotations, and only 1 parameter at 100% coverage. The description omits everything an agent would need to call this reliably: the conversion factor, which ton system is assumed, rounding/precision, and accepted input. For a unit-conversion tool where the result depends on the ton definition, this is a substantive omission.

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 documents the single 'value' parameter — baseline 3 applies. The description adds no syntax, range, or format guidance beyond the schema, but it doesn't need to. The 'value' description ('Value to process') is itself generic, and the tool description doesn't compensate, so no upgrade to 4.

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+resource: 'Convert kg to tons.' The direction is unambiguous (kg → tons), which is essential given the sibling x402-tons-to-kg performs the inverse. However, 'tons' is ambiguous (metric tonne vs US short ton vs UK long ton), and the description does not disambiguate, which for a unit-conversion tool is a meaningful clarity gap.

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?

Usage is implied by the name and description — the agent knows to call this when converting kilograms to tons, and the sibling x402-tons-to-kg provides the reverse alternative. But there is no explicit 'use this instead of x402-units-convert when...' guidance, and no mention of when to prefer the generic converter. Minimum viable.

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