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

Annotations already establish readOnly, idempotent, non-destructive, closed-world behavior, so the bar is lower. The description adds genuinely new behavioral facts beyond that: the result is derived from published rules with a cited source, no real SIREN is validated, and no side effects on orders occur.

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?

It is a single dense paragraph with the core rule front-loaded, followed by outputs, use cases, exclusions, and a source link. Every clause carries information, though the middle section lists several outputs at once and could be slightly tighter.

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?

An output schema exists, so return-value detail is not required, and the description usefully previews what is returned (online opening, commitment, payment methods). Combined with the explicit non-goals and source link, it is sufficient for an agent to call it correctly; only alternative-tool routing is absent.

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%, so the baseline is 3. The description still adds meaning by tying has_siren to the professional/SIREN requirement and by stating the actual eligibility threshold of 1–20 lines, which sharpens the intent of the lines parameter beyond its raw 0–1000 schema range.

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 gives a concrete verb and resource: it applies the published subscription rules to determine who can subscribe, and enumerates the resulting outputs (online opening, commitment, payment methods). It also distinguishes itself from adjacent concerns by stating it verifies no real SIREN and creates no order.

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?

It explicitly names the triggering questions ("puis-je souscrire ?", "est-ce sans engagement ?") and adds negative boundaries (no SIREN verification, no order creation). It stops short of naming which sibling to use instead, so it is clear context without explicit alternatives.

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