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

With no annotations supplied, the description carries the full behavioral burden. It does add genuinely useful context not in any structured field, namely the '5 free trial calls per signed wallet' limit and the signed-wallet auth requirement. It leaves key behavior undisclosed: whether conversion is base-1000 or base-1024, rounding/precision, and what the response looks like.

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?

Purpose is front-loaded in the first sentence, the parameter example follows, and the trial note closes. Only the prefix 'Data:' is wasted, and the free-trial line earns its place by conveying quota and auth. Nothing is padded or redundant.

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-parameter converter with no output schema and no annotations, the description covers purpose, units, an invocation example, and quota. It is still not complete enough for confident use because the two ambiguities that actually cause wrong answers, base-1000 vs base-1024 and output format/precision, are unaddressed.

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 0%, so the description must compensate for three undocumented parameters. It names all three (value, from, to), enumerates the accepted units, and gives a concrete from=MB,to=GB example, which is meaningful added value. It still omits accepted spellings/case (KB vs KiB vs kb), whether value is numeric or string, and behavior for unrecognized units.

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 a data size between bytes, KB, MB, GB, TB'. An agent immediately knows the operation and the unit family. However, it does not distinguish this from close siblings such as x402-data-size, x402-gb-to-mb, or x402-mb-to-gb, which appear to do overlapping work.

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 gives no when-to-use guidance and no alternatives or exclusions, despite a dense sibling set containing directly competing converters. The only operational hint is how to fill the parameters, which is invocation detail rather than selection guidance.

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