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

Annotations already declare readOnly, idempotent and non-destructive. The description adds real value beyond them by disclosing the visibility scoping rule (a key limited to some agents sees only its own sends) and the exact error shape (404 message_not_found for another agent's message).

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 and short, with the scoping caveat placed where it matters. The first sentence duplicates the title verbatim, which is mild waste, and the awkward mid-sentence line break slightly hurts readability.

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 one-parameter read tool with no output schema, the main ambiguity an agent faces (cross-agent visibility and the 404 result) is covered. It does not describe the possible status values returned, which is the only notable gap given there is no output schema.

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% and the single `id` parameter is fully documented as 'the id returned from a previous send.' The description's phrasing ('by the id the send returned') only restates the schema rather than adding format or constraint detail, so the baseline 3 applies.

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: look up the delivery status of a message previously sent via sendWhatsAppMessage or sendWhatsAppTemplate. The tie to those specific send tools separates it from generic message readers like get_conversation_message, though it never explicitly names that sibling to draw the contrast.

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 clear context: use it with the `id` a prior send returned, after calling one of the two named send tools. It does not offer explicit alternatives or when-not-to-use guidance, but the triggering workflow is unambiguous.

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