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

No annotations are provided, so the description carries the full burden. It does disclose the auth/quota context ('5 free trial calls per signed wallet'), which is genuine behavioral information about access and rate limits, but it says nothing about return format, behavior on invalid/non-numeric input, or edge cases like single-digit primes.

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?

One compact sentence that front-loads the definition, plus a short pricing/auth note. The leading 'Is Emirp Number:' label is mildly redundant with the tool name but costs little.

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 single-parameter boolean predicate with no output schema and no annotations, the definition of the condition is the essential information, and it is supplied. Only input-format constraints and expected return shape are absent, which is a minor gap for a tool this simple.

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 0% for the single 'value' parameter, so the description must compensate. It anchors the parameter's meaning (the number whose primality and reverse are tested) but gives no type or constraint guidance, notable because the schema types it as a string while the semantics are numeric.

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 states a specific predicate ('Checks whether value and its digit-reversed form are both prime and unequal'), which precisely defines the emirp concept rather than restating the name. It is distinguishable from neighboring primality tools like is-prime or is-circular-prime by the explicit two-condition definition, though it never names those siblings.

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 versus alternatives such as x402-is-prime, x402-is-circular-prime, or x402-is-palindromic-prime. The description only defines the concept, leaving routing entirely to inference.

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