Send a text message

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

The description adds meaningful behavioral context beyond the annotations by disclosing the asynchronous queueing behavior and the return shape (id and queued status). Annotations already convey read-write and non-idempotent traits, so the description supplements rather than repeats them.

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 sentences with no fluff. The purpose is front-loaded, behavior is stated next, and the usage caution is last. Every sentence earns its place.

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 sending tool with 100% schema coverage, no output schema, and annotations covering safety traits, the description covers the essentials: what it sends, the async behavior, and the expected result. It could mention idempotency or retries, but that is already documented in the idempotencyKey parameter.

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 100%, so the baseline is 3. The description adds little beyond the schema—'contact, group or channel' is already covered in the 'to' parameter description, and WhatsApp formatting is mentioned in the schema. The description does not compensate for or extend parameter meaning significantly.

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 states a specific verb ('Send') and resource ('text message') with the source ('linked number') and target types ('contact, group or channel'). This clearly distinguishes it from sibling tools like send_media, send_location, send_contact, and send_poll.

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?

It provides clear usage context: messages are queued and sent at the account's pace, and it warns to send only to people who expect it. It does not explicitly name alternatives or exclusion conditions (e.g., when to use reply_to_message), so it slightly misses the top score.

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