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

Annotations already flag this as a non-read-only, open-world, destructive operation, so the safety profile is covered. The description adds two things annotations cannot: a stable requestId makes retries safe (idempotency), and a 'pending' status does not mean the message was delivered. That delivery-semantics warning is genuinely valuable for an async send 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?

Three short sentences with no filler, and the consent precondition plus the idempotency note are front-loaded. It is terse to the point of being cryptic in places, and the language mismatch with the otherwise English tooling is a minor structural blemish.

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 an 8-parameter destructive messaging tool with no output schema and 0% schema coverage, the description covers only retry safety and delivery status. It says nothing about how channel affects required fields, when templateName/templateLanguage must be supplied, or what a successful response contains beyond 'pending'.

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 full burden, yet it only explains requestId (stability for retries). Six other parameters — channel, subject, contactId, parameters, templateName, templateLanguage — receive no semantic explanation anywhere, leaving template usage and channel selection opaque.

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 verb+resource pairing ('Envoyer un message') is identifiable, but the description never says this is the multi-channel conversation sender, so an agent cannot tell from the text why it would pick this over the sibling send_sms, send_whatsapp, or send_telegram tools. The channel enum in the schema supplies that meaning, not the description.

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 states a real precondition — explicit client agreement and recipient consent — which is useful when-to-use context. However, no alternatives are named and no when-NOT-to-use guidance is given, so routing between this tool and the per-channel siblings is left implicit.

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