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

No annotations are provided, but the description discloses two non-obvious behaviors: it performs only checksum validation ('Does not call INSEE') and it carries a real-world cost ('Paid $0.01 USDC Base x402'). It does not describe result format or invalid-input handling, but the disclosed constraints are valuable for an agent.

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?

Two short sentences with no filler. The core algorithm and caveats are front-loaded, and the paid note is clearly separated for scanability.

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 no annotations, no output schema, and no declared input parameters, the description is incomplete: it neither states what input the tool expects nor what it returns (e.g., boolean valid/invalid). The INSEE and cost caveats are helpful, but an agent still lacks enough operational detail to confidently invoke and interpret the tool.

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?

There are zero declared parameters and the schema only allows additionalProperties, so the rubric baseline is 4. The description adds that the subject is a SIRET/SIREN string, but it does not explain how the value should be passed to the tool, leaving invocation details to inference.

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 identifies the resource (SIRET/SIREN) and the method (Luhn/La Poste checksum), and distinguishes itself from an INSEE lookup by explicitly saying it does not call INSEE. It lacks an explicit verb like 'validates', but the noun phrase 'checksum' plus the tool name makes the purpose reasonably clear.

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 purpose implies usage when a SIRET or SIREN checksum needs verification, and the INSEE exclusion hints at when not to use it for official registry checks. However, no sibling alternatives such as check_iban or siren_from_siret are named, and there is no explicit guidance on when to prefer this tool over them.

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