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

With no annotations at all, the description carries the full burden, and it does disclose genuinely non-obvious traits: a $0.05 paid cost, the exact return semantics (remainder 0-96, valid=1), and that the computation is a deterministic pure calculation. It omits error behavior for non-alphanumeric or Unicode input and any rate-limit detail, which keeps it below a 5.

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?

Four short, front-loaded sentences: price first, then operation, then return contract, then use cases. Every sentence carries information, though 'Verified via Rust WASM engine' is closer to a trust signal than operational guidance.

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 pure computation with no output schema, the description supplies what an agent needs: cost, what is computed, what is returned, and the domain of use. Only the failure mode for invalid input is left unstated.

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 100% for the single 'input' parameter, and the schema already says it is the alphanumeric string to compute on. The description reinforces the alphanumeric constraint but adds no format, length, or normalization guidance beyond the schema, so the baseline 3 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?

Names a specific verb ('Calculate') and a specific algorithm ('ISO 7064 Mod 97-10 remainder') with an explicit scope ('any alphanumeric string'), and situates it as the generic primitive behind IBAN/LEI validation. It stops short of explicitly contrasting itself with the iban_check and lei_check siblings, so an agent must infer that this is the low-level building block rather than the full validators.

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?

Usage is implied through the listed domains ('IBAN, LEI, and custom identifier validation') and the 'custom identifier' phrase hints at when this beats the specialized checks. However, there is no explicit when-not guidance and no named alternative such as 'use iban_check for full IBAN structure validation instead,' leaving the routing decision to inference.

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