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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds value by disclosing the returned fields (address, activity code, status, head-office flag), which matters since there is no output schema. It does not describe behavior on an unknown or invalid SIRET, which keeps it from 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?

Two sentences, no filler; the positive trigger and return contents come first, the routing exclusion second. Every clause carries information an agent needs to select and call the tool.

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?

Single required parameter with full schema documentation, and the description covers purpose, trigger, return contents, and the competing alternative. Absence of an output schema is offset by the enumerated return fields.

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% and the schema itself documents the 14-digit SIRET with spaces allowed and min/max length. The description restates 'SIRET (14 digits)' but adds no format, normalization, or validity semantics beyond that. Baseline 3 is appropriate.

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 (retrieve a single establishment by SIRET) and enumerates what it returns: address, activity code, status, head-office flag. It also explicitly contrasts with get_company, so the agent can distinguish it from the sibling without reading schemas.

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?

Gives an explicit trigger condition ('when the user gives a SIRET (14 digits)') and an explicit exclusion with a named alternative ('Do not use to find all establishments of a company; get_company lists them'). Both when-to-use and when-not-to-use are covered.

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