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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description usefully adds that the source is a public register, but it omits what happens when nothing matches, whether a name query can return multiple hits, and any rate/availability constraints on the external register.

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?

Front-loaded with the purpose and format before the auxiliary context, and no sentence is wasted. The 'Args:' docstring artifact is slightly rough but functional and arguably helps an agent map the field.

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?

With no output schema, the description does convey the return shape via the FR123456_01ABCD format example, which is the key thing an agent needs. It stops short of describing no-match or multiple-match behavior, the one gap that matters for a single-param lookup 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?

Schema description coverage is 0%, so the description carries the full burden and does so well: it enumerates the accepted input forms — SIREN (9 digits), SIRET (14 digits), an identifier of the FR…_… form, or a company name of at least 3 characters — including the length constraint. This is meaningfully more than the bare 'query' string in the schema.

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 (Find) and resource (French EPR unique identifiers / identifiant unique REP) with the authoritative source (public ADEME register, SYDEREP) and a concrete format example. The domain is clearly distinct from every sibling tool (HTML/text checkers, rule lookups, GPSR generators), so an agent can route without ambiguity.

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 second sentence gives business context ('a producer covered by an EPR scheme must show them in its terms of sale'), which implies when this is relevant, but there is no explicit instruction on when to call it versus doing nothing, nor any exclusion or precondition. Usage is inferable rather than stated.

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