wa_send_template

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

With empty annotations, the description carries full burden. It discloses the async nature (returns only accepted message ID, status via webhooks), the requirement for APPROVED template, the distinction that phone_number_id is the sender not destination, and the limitation about header media requiring uploaded media handles. This is comprehensive for a send operation.

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 well-organized into 'When to use,' 'Requirements,' 'Returns,' and 'Limitations' sections. Each sentence provides necessary operational information without redundancy. It is concise given the complexity of the tool and the need to clarify common pitfalls (e.g., sender vs recipient ID).

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 tool with 5 parameters, no output schema, and empty annotations, the description fully equips an agent: purpose, usage scenarios, prerequisites, parameter clarifications, return value, and limitations. It even addresses asynchronous delivery behavior. No critical information is missing for correct invocation.

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 extra value by clarifying that phone_number_id is the sender ID 'NOT the destination phone,' and by giving a concrete JSON example for components_json with body parameters. It also notes when components_json is required (variables, header media, buttons), which goes beyond the schema's generic description.

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 description opens with a specific verb+resource: 'Send a pre-approved template message to a recipient on WhatsApp.' It clearly distinguishes from siblings like wa_create_template (creation), wa_get_templates (retrieval), and wa_get_message_status (status) by focusing on outbound message delivery.

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?

The 'When to use' section explicitly lists scenarios (outbound notifications, marketing, utility, first-contact) and provides a clear boundary with the 24-hour customer service window. It also references wa_get_templates as a prerequisite verification step. It doesn't name direct sibling alternatives for sending, but the context is strong enough for an agent to decide when to invoke it.

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