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

Annotations already cover read-only, open-world, idempotent, and non-destructive behavior. The description adds meaningful behavioral context: it is FREE and needs no API key, the result explicitly notes the registration limitation, and the agent is instructed to pass the caveat intact and never guess. No contradiction with annotations.

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?

About four sentences with no filler: first sentence gives the action and dataset, second describes the result, third explains the limitation and required user handling, fourth states cost and auth. Every 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?

For a single-parameter lookup with no output schema and full annotation coverage, the description gives everything needed to select and invoke the tool correctly: target entity, accepted identifiers, dataset, result meaning, limitation, and handling instructions. The absence of an explicit not-found behavior is minor and does not affect tool selection or invocation.

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 input schema already provides 100% coverage of the lone query parameter, including acceptable forms. The description repeats SIREN/SIRET/name formats but does not add new parameter semantics beyond what the schema states, so the baseline score of 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?

States a specific verb and resource: look up a French company by SIREN, SIRET, or name in INSEE SIRENE open data. It clearly identifies what the tool confirms (existence and active status) and distinguishes itself from siblings by explicitly saying it cannot confirm platform registration.

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?

Places the tool in the 2026-2027 French e-invoicing mandate context and gives a clear when-not: it cannot confirm registration with an approved platform. It does not explicitly name a sibling alternative like list_approved_platforms, but the exclusion is clear and actionable.

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