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

No annotations exist, so the description is the only behavioral disclosure. It states the intended calculation, but it does not explain how a torus surface area can be produced with zero input parameters, what assumptions are used, or what the return value looks like. Those omissions are significant because there is no output schema to fill the gap.

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?

At five words plus a redundant label, the description is extremely short and front-loaded. The 'Torus Surface:' prefix repeats the tool name, so it does not fully earn its place, but there is no wasted technical detail.

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 no-output-schema tool with no annotations, the description should clarify the return value and any implicit inputs. It only states 'Surface area of torus,' leaving unclear what number is returned and how the torus is defined without parameters. This makes the tool's contract incomplete.

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 input schema has zero properties, so schema coverage is complete by default. With no parameters to document, the description does not need to add parameter-level detail; the 0-param baseline applies.

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 names the exact resource (torus) and quantity (surface area), so an agent can tell what calculation is offered. It is clear but does not explicitly contrast with sibling tools like x402-torus-volume, so sibling differentiation is only implicit.

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 phrase 'Surface area of torus' implies the use case: when a torus's surface area is needed. However, it gives no explicit when-to-use guidance, no prerequisites, and no direction toward alternatives such as x402-torus-volume.

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