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

No annotations are provided, so the description carries the full behavioral burden. It mentions the wallet-based free trial condition but omits what the tool returns, whether the side input is validated, units, and error behavior, leaving key operational context undisclosed.

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 text is short and front-loaded, but the first fragment duplicates the tool name rather than adding useful detail. The free-trial sentence is concise but does not help an agent invoke the calculation correctly.

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 calculation tool with no output schema and no parameter documentation, the description should at least clarify the input and return value. Instead it stops at the mathematical concept and a trial-call note, which is insufficient for confident invocation.

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 coverage is 0% and the single `side` parameter is undocumented in the schema. The description only implies that a cube side is needed and never names the parameter, explains its string format, or specifies units.

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 repeats the tool name ('Cube Space Diagonal') and restates the same concept ('Space diagonal of a cube'), so it is essentially tautological. It gives no verb, scope, or differentiation from siblings such as x402-cube-diagonal or x402-cuboid-diagonal.

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 comparison to related diagonal tools. The free-trial note is access information, not guidance on selecting this tool versus alternatives.

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