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

Without relying on annotations, it discloses billing semantics (charged only if status=completed for sync, only on delivery for async), idempotency behavior (same result, no double billing via request_key), budget enforcement (nothing executes beyond max_price_eur), required API key, and the async status=queued + run_id lifecycle. This is rich operational context well beyond readOnlyHint=false and openWorldHint=true.

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 core action and return, then parameter notes, then the sync/async billing rules. Dense but each sentence carries information; minor redundancy in restating billing twice ('facturé seulement si…' / 'Facturé seulement à la livraison').

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 high-complexity, billable, async-capable tool with an output schema present, the description covers billing, idempotency, auth, and async tracking adequately. The remaining gap is guidance on what belongs in 'params' and which 'service' values are valid, which the sibling list_services would presumably supply.

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 burden. It meaningfully explains max_price_eur, quote_id, and request_key, but says nothing about the two required parameters 'service' (which services are valid) or the free-form nested 'params' object, leaving 2 of 5 parameters undocumented in both schema and description.

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?

Starts with a specific verb+resource ('Exécute un service') and states what it returns (structured result with sources, limits, missing items). It also distinguishes two operating modes (sync vs async) and names the sibling get_run for async follow-up, though it does not differentiate itself from quote_service or list_services.

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 routes the agent conditionally: sync returns immediately, async returns a run_id 'suivez-le avec get_run'. It also tells the agent to reuse request_key on retry. However, it never states when to call run_service versus the quote_service/list_services siblings, so the choice among alternatives is left implicit.

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