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

With no annotations, the description carries the full behavioral burden. It does disclose a real trait an agent cannot get from structured fields: a quota ('5 free trial calls') tied to a 'signed wallet' (auth requirement), plus 'Safe' implying side-effect-free evaluation. It still omits return format, error behavior on unsafe input, and permission details.

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?

Extremely short and front-loaded with no filler, but it is under-specified rather than concise: two fragments that do not convey enough to call the tool 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 tool with three undocumented parameters, no annotations, and no output schema, the description leaves too much unexplained. It provides no parameter meaning, no return-value context, and no behavioral specifics beyond the trial quota.

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?

Three string parameters (q, expr, expression) at 0% schema description coverage, and the description explains none of them. It does not clarify which parameter is the expression, whether they are aliases, or how they interact, so it fails to compensate for the coverage gap.

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 resource ('Math') and hints at function ('Safe math expressions'), suggesting it evaluates arithmetic expressions. However, there is no verb and it largely restates the tool name 'x402-math', leaving the exact operation vague against hundreds of sibling calculators like x402-area or x402-percent.

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, no mention of alternatives among the many math siblings, and no conditions for selecting this tool. The only added sentence is a pricing note about free trial calls, which is not usage guidance.

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