Send SMS from your phone

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

Beyond the annotations, the description discloses important side effects: each recipient consumes plan allowance, carrier costs may apply, and a successful accepted=true response is not proof of delivery. It also gives retry guidance consistent with the non-idempotent annotation, adding meaningful safety context.

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 purpose is front-loaded and each sentence adds useful information: cost impact, device defaulting, return semantics, delivery caveat, and retry warning. There is no redundant or wasted text.

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 side-effecting tool with no output schema, the description explains the return shape enough to set expectations and warns that acceptance is not delivery. It is nearly complete, but the missing explanation of sim_subscription_id leaves one parameter semantically opaque.

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 0%, so the description must carry parameter meaning. It clarifies exact-message behavior, E.164 recipient expectations, and the device_id default, but it never explains sim_subscription_id and does not cover schema limits such as max recipients or message length.

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 gives a specific verb and resource: sending an exact SMS message to explicit international E.164 recipients through the user's own Android SIM. This clearly differentiates it from sibling tools such as listing messages, reading received SMS, or checking send status.

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 gives clear operational guidance: omit device_id to use the account default phone, check send status afterward, and never automatically retry on an unknown outcome. It does not explicitly enumerate when not to use it or name alternatives, but the send-only purpose is unambiguous among siblings.

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