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

No annotations are provided, so the description carries the full burden of behavioral disclosure, and it adds nothing about computation method, units, output format, or edge cases. It is a tautological restatement of the name/title, earning the minimum score.

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?

It is a single short sentence with zero waste, but it is under-specified rather than concise; front-loading is fine but the content is too thin.

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 geometry calculator with no annotations, no output schema, and 100% schema coverage, the description is technically sufficient to call the tool, but it omits units, formula expectations, and any behavioral notes that would help an agent use it correctly. It is incomplete as a guide.

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 the schema already documents all three parameters (width, height, length) with their names. The description adds no extra meaning beyond the schema, which is the baseline 3 when schema coverage is high.

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?

States a specific verb+resource ('Surface area of rect prism'), which is clear enough to distinguish from siblings like x402-rect-prism-volume or x402-prism-volume. It is essentially a restated title, but the intent is unambiguous, so it is 4 rather than 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?

There is no guidance on when to use this tool vs the many sibling volume/surface tools, nor any mention of prerequisites or units. The description offers no context beyond the bare purpose.

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