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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered; the description adds genuinely new behavior: visibility is scoped by which agents the key or assistant can reach, and out-of-scope ids return `404 message_not_found` indistinguishable from an unknown id. That 404-equivalence detail materially changes how an agent should interpret a failure. It does not describe latency or delivery-state progression, keeping it at 4.

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?

The title sentence is front-loaded and the scoping caveat follows it, so the essential use case is read first. The second paragraph is dense but every clause (which sends, which key, the 404 rule) carries information; a small amount of repetition of the first line exists between title and body.

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?

There is no output schema, so the description is the only place the return value could be explained — yet it never says what a status looks like (e.g. sent/delivered/read/failed) or whether it is polled over time. For a status-lookup tool with no output schema, that is a real gap, though the access-scoping and 404 semantics are well covered.

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% for the single parameter and the schema already says 'The `id` returned from a previous send'; the description's 'by the `id` the send returned' restates the same fact. Baseline 3 applies when the schema carries the parameter meaning.

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?

Names a specific verb ('look up the status') and a specific resource ('a previously-sent message'), and ties it to the exact producer tools (`sendWhatsAppMessage` / `sendWhatsAppTemplate`) plus the `id` they return. An agent can distinguish this from `get_whatsapp_template`, `list_conversation_messages`, or `get_tool_run` without opening the schema.

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?

States the precondition clearly: this is for messages already sent via the two send tools, and the input is the id the send returned. It does not explicitly exclude alternatives (e.g. `list_conversation_messages` for browsing a thread), so it stops short of full when/when-not guidance, but the usage context is unambiguous.

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