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 not say whether the output includes a '%' symbol, how the 'decimals' parameter affects rounding, or how a malformed value is handled — all behaviorally important for a formatter.

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?

A single short sentence, front-loaded with the verb. It is efficient, though the prefix "Format Percent:" mildly restates the tool name before the informative clause.

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 two-parameter formatting utility with no output schema and no annotations, the description is minimally adequate but leaves the output shape (percent sign, precision) unspecified. It is enough to attempt a call but not to predict the result confidently.

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 parameters are already documented by the schema, giving a baseline of 3. The description adds no extra meaning about the role of 'decimals' or the expected input format of 'value', so it neither compensates nor elevates.

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 clear verb ("Format") and resource ("a number as a percentage"), so an agent understands the transform. However, it does not distinguish itself from close siblings like x402-percent, x402-percent-of, or x402-ratio-to-percent, so the differentiation that would earn a 5 is absent.

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 guidance and no mention of alternatives among the many percent-related siblings (x402-percent, x402-ratio-to-percent, x402-fraction-to-percent). The agent is left to infer the selection context entirely.

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