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 states the conversion but does not disclose return format, precision/rounding behavior, unit validation, or what happens with non-numeric input. For a math tool, expected behavior is largely self-evident, but the description adds nothing beyond the bare operation.

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 one short sentence, front-loaded with the operation and fully self-contained. No wasted words, no redundancy.

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 math conversion tool with one schema-documented parameter, no annotations, and no output schema, the description is minimally adequate. It states the operation but omits return format (number? string?) and precision, which an agent would need to integrate the result. Adequate but with clear gaps.

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 already documents the single 'value' parameter. The description adds no parameter-level detail (e.g., expected numeric format, range). Baseline 3 is appropriate when the schema does the heavy lifting and the description adds nothing extra.

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 psi to bar.' The tool name itself encodes the same direction, and the description matches exactly with no ambiguity. Given the massive sibling set containing many unit converters, the naming convention (x402-psi-to-bar vs x402-bar-to-psi) disambiguates direction clearly.

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?

For a simple one-parameter unit converter, the usage guideline is implicit and complete: use this when you have a value in psi and need it in bar. The reverse sibling (x402-bar-to-psi) exists and the naming pattern makes the choice obvious. No exclusions are needed for a single-purpose conversion tool.

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