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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, so the description does not need to repeat safety. It adds valuable behavioral context: the registry coverage (~40M establishments), that address data is geocoded by INSEE, and the specific fields returned (status, NAF, creation date, address, head-office flag, parent company). This goes beyond annotations and helps the agent set expectations.

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?

The description is well-structured and front-loaded: the first sentence states the purpose and input, the second lists returns, and the third adds registry context and alternative tools. Every sentence contributes useful information with no fluff or repetition.

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?

Given the tool has only one parameter and an output schema exists, the description is complete. It covers what the tool returns, when to use it, what data source it accesses, and how it differs from siblings. Nothing an agent needs to invoke it correctly is missing.

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 100%, so the schema already fully documents the single 'siret' parameter, including the exact 14-digit pattern and space-stripping behavior. The description's mention of '14-digit SIRET number (SIREN + NIC)' is redundant with the schema. No additional semantic value is added beyond 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?

The description clearly states the tool's purpose with a specific verb ('Retrieve'), resource ('official record of a French establishment from the INSEE Sirene registry'), and required input (14-digit SIRET). It distinguishes itself from siblings by naming insee.company.by_siren and insee.establishment.search as alternatives, making its unique role explicit.

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?

Explicitly provides when-to-use guidance: it states to use insee.company.by_siren for parent-company-only lookups and insee.establishment.search for searches by postal code or city. This directly routes the agent to the correct tool based on the lookup type.

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