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

With no annotations, the description carries the full transparency burden and does so well: it discloses the filing history fields, the conditional accuracy policy ('says not_covered rather than guessing'), the 24h cache, and the price. This is rich behavioral disclosure beyond a simple read-only implication.

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 dense but every sentence adds value: purpose, query syntax, return fields, limitation policy, cache, and price. It is front-loaded with the core purpose and efficiently structured.

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, the description covers input validation, return elements, and fallback behavior. It could add error cases (e.g., invalid Luhn, no filings found), but the main operational behavior is sufficiently complete.

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 only lists 'siren' with no description, but the description compensates fully by giving the query format (?siren=), an exact example, the 9-digit length, and Luhn validation. This is more than enough for an agent to format the parameter correctly.

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 specifies it returns annual accounts filed with the French RNE (INPI), and details the filing history plus headline financial figures. This verb+resource scope is distinct from sibling tools like lookup_company_fr or check_insolvency_fr.

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 phrase 'Annual accounts filed with the French RNE' and 'which is a KYB signal in itself' make the intended context clear—French financial/KYB checks. It does not explicitly name when-not-to-use or alternatives, so it stops short of a 5.

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