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

No annotations exist, so the description carries the full burden of behavioral disclosure—and it reveals nothing. It does not state what the tool evaluates, what inputs it operates on, what edge cases exist, what output it returns, or whether it is a pure read/predicate operation. A one-line tautology provides no behavioral transparency at all.

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, but this is under-specification rather than conciseness—every token is redundant with the tool name. It contains no information that could not be inferred from the tool name itself, so no sentence earns its place.

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?

With no annotations, no output schema, and an empty input schema, the description is the only source of context, and it is entirely inadequate. It fails to disambiguate from x402-is-fermat and x402-is-fermat-prime-num, does not explain what input or output is involved, and leaves an agent with no way to invoke or interpret the tool correctly.

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 tool has zero parameters, so there is technically nothing to document, but the description fails to explain what the tool even operates on, making the schema's empty properties unintelligible. Since a 0-param tool cannot receive input through the schema, the description should clarify the subject of the check; instead it adds nothing, leaving the tool's contract completely opaque.

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 'Is Fermat Prime: Is Fermat Prime' is a pure tautology—it merely restates the tool name and adds no verb, resource, or scope detail. It does nothing to distinguish this tool from near-identical siblings like x402-is-fermat and x402-is-fermat-prime-num, leaving an agent unable to tell which one to call.

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 provides zero guidance on when to use this tool versus alternatives. With siblings x402-is-fermat and x402-is-fermat-prime-num covering the same apparent domain, no conditions, exclusions, or selection criteria are given; an agent must guess which tool is appropriate.

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