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

With no annotations, the description carries the full burden of behavioral disclosure, but it reveals nothing. It does not state that the tool converts bytes to a human-readable file size, what units will be used, how rounding works, or 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?

The description is extremely short but it wastes that space on a redundant restatement of the name. This is under-specification rather than genuine conciseness; every sentence should add information, and this one adds none.

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 tool with two parameters, no annotations, and no output schema, the description is completely inadequate. An agent is given no information about expected input format, return value, error behavior, or how to choose between parameters, so it cannot reliably invoke this tool.

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 both 'bytes' and 'value' have descriptions and the baseline is 3. However, the description adds nothing beyond the schema and does not clarify the relationship between the two parameters, leaving ambiguity about whether both are accepted, which takes precedence, or if they are aliases.

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 'File Size Humanize: File Size Humanize' is a tautology: it restates the tool name without any verb, action, or result. It gives no indication of what the tool does beyond what the name already suggests, and it does not differentiate this tool from siblings like x402-data-size-humanize or x402-format-bytes.

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 guidance on when to use this tool versus alternatives. The description does not mention any related tools, conditions, or exclusions, so an agent cannot determine whether to choose x402-file-size-humanize over x402-data-size-humanize or x402-format-bytes.

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