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

No annotations are present, so the description carries the full burden of behavioral disclosure. It only states the transformation intent and says nothing about rounding behavior, locale conventions, decimal places, output format, or edge cases. An agent cannot predict how 0.1234 or 12.345 will be rendered.

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 short and front-loaded, with no filler. It loses one point because 'Format Percent:' essentially restates the tool name and consumes space without adding information beyond the sentence that follows.

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 formatting utility with no output schema, no annotations, and an empty input schema, the description is insufficient. It does not explain how the number is provided, what the output looks like, or how it differs from related percent and formatting siblings. An agent could not confidently invoke or interpret results based on this definition.

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?

The schema has zero parameters, which sets the baseline at 4. The description adds conceptual meaning by indicating that a numeric value is the subject, even though no parameter is defined in the schema. It does not specify how the number is supplied, but with an empty schema the description contributes what little semantics exists.

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 and resource: 'Format a number as a percentage.' It is obvious what the tool is supposed to do. However, it does not differentiate itself from the many sibling formatting tools such as format-decimal, percent, or percentage-of, which keeps it at a 4 rather than a 5.

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 guidance on when to use this tool versus the numerous related percent/formatting tools. There is no mention of alternatives, exclusions, or context. Usage context is only vaguely implied by the name and one-line purpose.

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