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

Annotations only carry openWorldHint=true, so the description does real work: it discloses the 24h customer-service window constraint, the requirement that the flow be published, and the token round-trip via the message:flow:response webhook. It stops short of covering failure behavior, rate limits, or what the call returns on success, which keeps it from a 5.

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 sentences, front-loaded with the core action, then the eligibility constraint and alternative, then the two semantically tricky params. No filler and no restatement of the name.

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 10 params, 4 required, a nested data object, and no output schema, the description covers the essential calling context: preconditions, alternative path, and the token/data mechanics. It leaves the response shape (message id, immediate failure modes) unspecified, a minor gap given the tool exists to hand off to a webhook.

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 adds light context around token (matched to your own record and returned in the webhook) and data (prefill), but both points are already in the schema's own parameter descriptions, and the UI text fields (header/body/footer/cta) and screen are untouched.

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?

States a specific verb and resource ("Send a published WhatsApp Form ... as a native interactive message") and frames the mechanism (one message instead of a question-by-question flow). This is clearly differentiable from send_whatsapp_message (plain message) and create_whatsapp_template (template authoring) in the sibling list.

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?

Gives an explicit when-not plus the alternative: "Only works within the 24h customer-service window; to start a conversation, send a template whose button opens the form." The agent knows both the eligibility gate and the fallback path without opening a schema.

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