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

With no annotations, the description carries the full burden, and it does disclose behavior: rounding to two decimals, unit appended to the result, and the fallback from 'bits' to 'value'. It also adds payment context ('5 free trial calls per signed wallet'), which is genuinely useful behavior beyond any structured field. It remains silent on error behavior for malformed input and on the exact unit casing returned.

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?

One compact sentence carries purpose, rounding rule, fallback precedence, and output shape, with the core operation front-loaded. The free-trial badge is marketing-flavored but still conveys useful auth/pricing information, so it mostly earns its place.

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 two-input formatter with no output schema, the description covers the essentials: input source, precedence between the two inputs, precision, and output shape. Only input-type expectations and error handling are left implied, which is a minor gap at this complexity level.

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% for two optional string parameters, so the description must compensate. It does explain the key relationship ('reads bits and falls back to value'), which is real added meaning, but leaves open what format 'bits' accepts (numeric string? prefixed?) and whether 'value' is a raw number or a pre-formatted string.

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 opens with a specific verb and resource ('Scale a bit count to b/Kb/Mb/Gb/Tb with up to two decimals') and states the append-unit behavior, so an agent can identify it as a bit-specific formatter. It does not explicitly distinguish itself from nearby siblings such as x402-format-bytes or x402-data-size-humanize, which handle the byte equivalents.

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?

There is no when-to-use or when-not-to-use guidance and no named alternative. An agent working in a catalog of hundreds of formatting tools gets no signal that this is the bits variant rather than the bytes one, other than the word 'bits' in the first clause.

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