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

Annotations already disclose mutation, open-world, non-idempotent, and destructive behavior. The description adds meaningful constraints: template approval is required, the 24h-window context, and per-recipient results. It stops short of explaining rate limits, consent requirements, or irreversibility beyond the destructive hint.

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 description is front-loaded with the action and key constraint, and every clause adds useful information. It is dense and uses semicolons/parentheses rather than clean sentences, but it avoids redundant filler.

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 send tool with no output schema, the description covers purpose, account/template selection, approval prerequisite, and return shape ('per-recipient results'). It could go further on error behavior, rate limits, and permissions, but is largely complete given the annotations.

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 must carry parameter meaning. It successfully maps the account options (wp_account_id or wp_account_uuid), template selection paths (ID/UUID or name + language), and components as Meta template variables, though it does not explicitly describe the 'to' parameter by name or detail component format.

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 an approved WhatsApp template') and clarifies scope ('to one or many numbers'). It distinguishes this from sibling messaging tools by noting it is 'the only way to open a conversation outside the 24h window'.

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?

Explains the key usage context (opening a conversation outside the 24h window) and the prerequisite that the template must be APPROVED. It does not explicitly name alternatives like send_sms or send_email, but the WhatsApp-specific context is clear.

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