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

Beyond the write annotation, the description discloses the two-phase preview/confirm behavior, the unofficial Wacli client, and the account-restriction risk. This gives the agent material safety information that annotations alone do not convey, and it does not contradict the readOnlyHint=false/destructiveHint=false annotations.

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?

Four purpose-built sentences front-load the action and then cover the critical caveat, workflow, and risk. No sentence is filler; the warning earns its place because it changes the agent's risk assessment.

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?

With an output schema present and useful annotations, the description covers prerequisite ID provenance, the preview/send workflow, and the ToS risk. Nothing needed to invoke the tool correctly appears to be missing.

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 input schema already documents all three parameters (100% coverage), so the description does not need to repeat types. It adds crucial semantics for chat_id ('never fabricate IDs') and for confirm (preview vs. actual send), going beyond the schema's baseline descriptions.

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 and resource: 'Sends a text message to a WhatsApp chat.' It also clarifies the chat_id must come from whatsapp_list_chats, narrowing the tool's role among the many messaging siblings.

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 gives concrete workflow guidance: chat_id must come from a prior whatsapp_list_chats call, and confirm=false is for preview while confirm=true actually sends. It does not explicitly name alternatives such as whatsapp_send_file for file messages, so it stops short of a full exclusion-based usage rule.

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