send_sms

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

The annotations already indicate destructive/read-only/idempotent hints, and the description adds material context beyond them: charges may be incurred, the account is changed, verification is required, and the returned history can update asynchronously. No contradiction with 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?

Two tight sentences, front-loaded with the most decision-relevant warning about charges and state changes before the action. Every clause adds information and no schema details are repeated.

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 5-parameter destructive tool with no output schema, it covers prerequisites, side effects, costs, and the async return behavior. It could specify message/recipient expectations or failure semantics explicitly, but the schema plus warning make it reasonably complete.

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?

With 60% schema coverage, the schema leaves message and recipient undocumented except for the recipient pattern. The description adds no per-parameter meaning beyond the generic 'send an SMS' and the SMS-capable extension hint, so it does not compensate for the gap.

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?

States a specific verb and resource: 'send an SMS' on the SIPGATE account, with an added constraint 'after verifying an SMS-capable extension'. The action is unambiguous and naturally distinguished from siblings like initiate_call and set_dnd.

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?

Provides clear context for when to invoke: send an SMS after verifying an SMS-capable extension. It also signals prerequisites and cost/state-change implications, but it does not name alternatives or explicit when-not-to-use scenarios.

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