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

No annotations are provided, so the description carries the full burden. It does disclose useful behavior beyond structured fields: the upstream source, the fields returned, and cost ('Flat 30 points per successful run', which also implies failures are not billed). It says nothing about not-found/invalid-number behavior, rate limits, or auth requirements for a zero-annotation tool.

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, zero filler. Scope and source are front-loaded, the returned payload is enumerated compactly, and the cost note is a single short clause at the end.

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 and no annotations, the description appropriately enumerates the returned fields and the billing model, which is what an agent needs here. It is only thin on failure/edge-case behavior for a missing or malformed registration number.

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% and the single parameter already documents 'Registration number or registry URL' with an example (552032534). The description restates the same accepted forms without adding format rules (e.g. SIREN vs SIRET length, URL shape), so the schema does the heavy lifting and baseline 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?

Specific verb (get), scoped resource (one company), named source (France registry RNE/INPI), and the keying identifier (registration number or registry URL) are all stated. The 'one company by identifier' framing inherently distinguishes it from the sibling lookup-by-query tool run_fr_companies_search, and the returned field list (name, status, registration date, address, legal form) sets expectations.

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?

Usage is only implied: the agent infers it should call this when it already has a registration number or registry URL. No explicit when-to-use/when-not statement and no alternatives (run_fr_companies_search, run_fr_company_documents) are named or routed away from.

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