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 does disclose that conversion is driven by from/to unit names, which is the key behavioral fact for a pure calculator, but it says nothing about return shape, rounding/precision, or whether unsupported units error out. Adequate for a stateless computation, thin for a no-annotation tool.

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?

Two short sentences, front-loaded with the operation and then the argument shape. The leading 'Data:' label is mild noise, but nothing else is wasted.

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 3-parameter, no-annotation, no-output-schema tool the description covers the essential call shape but leaves return format and error behavior undocumented, and ignores the existence of a near-duplicate sibling. Enough to call it correctly, not enough to call it confidently over the alternative.

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?

Nominal schema coverage is 100%, but the schema descriptions are tautologies ('To to process', 'From to process', 'Value to process') so they carry almost no meaning. The description repairs that by defining value as the quantity and from/to as unit names with a concrete example, plus the supported unit set. It stops short of enumerating the accepted spellings (kb vs KB, GiB, etc.).

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 and resource: convert a data size across bytes/KB/MB/GB/TB. An agent can tell what it does, but the definition never distinguishes itself from the near-identical sibling x402-data-size (nor from x402-data-size-humanize, x402-gb-to-mb, x402-mb-to-gb), which is a real selection hazard given this catalog.

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 only implied by the parameter example '(e.g. from=MB,to=GB)'. There is no statement of when to pick this over the many unit-conversion siblings or when it is not appropriate, and no exclusions. Minimum viable.

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