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

With no annotations, the description carries the full burden. It discloses the exact validation algorithm (Luhn checksum) and a non-obvious behavioral caveat (the La Poste SIREN exception is not applied). However, it does not state what the tool returns (boolean, error, etc.) or whether it has side effects, leaving a minor gap.

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 sentences, front-loaded with the core purpose and immediately followed by a critical caveat. No wasted words.

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 simple validation tool with no output schema, the description covers purpose, algorithm, and an exception. The only missing piece is the return value format, which would help an agent interpret results, but the core information is present.

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%, and the description compensates by defining what a SIRET is (14-digit French business establishment number), adding semantic meaning beyond the schema's pattern constraint. It does not describe the wrapper 'payload' object, but for a single nested parameter the added context is sufficient.

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 verb (validate) and resource (French SIRET, 14-digit business establishment number) with the validation method (Luhn checksum). It clearly distinguishes itself from generic siblings like validate_luhn or validate_ean by naming the exact standard.

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 strongly implied by the specific naming of SIRET and the validation method, but the description never explicitly states when to use this tool versus alternatives (e.g., 'use this instead of validate_luhn for French SIRET numbers'). No exclusions or conditions are provided.

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