Send a WhatsApp chat message

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

The description adds substantial behavior beyond the annotations: the message is handed to a background daemon, the call waits up to 15 seconds for delivery confirmation, and the message cannot be unsent because real people may read it immediately. This is exactly the type of context annotations alone do not provide.

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?

Three tight sentences convey the action, the precondition, the execution path, the timeout behavior, and the irreversibility. Every sentence earns its place, and the core action is front-loaded.

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 two-parameter tool, the description covers the key operational context: prerequisites, async handoff, delivery wait, and human impact. It does not describe the return value or failure behavior on timeout, which is a minor 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 both required parameters are described in the schema. The description adds no new parameter-level detail beyond restating the allowlist/canPost condition already present in the jid schema 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 clearly states the verb and resource: sends a text message to a chat, with the specific precondition that the chat must be allowlisted and have canPost enabled. It is clearly distinct from sibling tools like list_chats and read_chat_messages, but it does not explicitly name or contrast those alternatives.

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 implies when to use the tool by framing it as sending a message and requiring an allowlisted chat with canPost enabled. However, it does not explicitly state when to use this tool versus siblings, nor does it mention alternatives like read_chat_messages for reading conversations.

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