Send a WhatsApp text message

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

Adds crucial real-world context: the message is actually sent from the user's account, there is no undo, and confirmation is advised for sensitive content. This goes beyond the annotations, which only indicate it's a write 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?

Two concise sentences with the primary action stated first and the safety warning following. No fluff, well-structured.

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 simple send-text tool, the description covers the essential purpose and the most important caveat (no undo). It doesn't need to explain return values since there's no output schema, and the annotations cover the technical write semantics.

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?

The schema already provides descriptions for all parameters (100% coverage). The tool description does not add additional parameter context beyond what is in the schema, so it remains at baseline.

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?

Clearly states the action 'Send a text message', specifying the resource (text message) and distinguishing from media or poll sending. The verb and object are explicit.

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 description indicates the tool is for sending text messages but does not explicitly contrast with sibling tools like send_media or send_poll. It provides a cautionary note about confirming sensitive content, which offers some usage guidance but not clear selection criteria.

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