send_sms

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

No annotations are provided, so the description must carry the full burden of behavioral disclosure. The description only says 'Send SMS via Voximplant', which implies a mutation but does not mention side effects, permission requirements, rate limits, or any other behavioral traits. This is almost entirely uninformative for an agent assessing the safety or consequences of calling the tool.

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 description is a single concise sentence that does not waste words. It is front-loaded with the core action, but it is arguably under-specified rather than efficiently concise. It earns a 4 because it is short and clear, though it sacrifices substance for brevity.

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 tool with three required parameters and no output schema, the description is too sparse to provide contextual completeness. It fails to mention when to use this tool versus send_a2p_sms, any prerequisites (e.g., phone number format), or what happens after sending. Given sibling tools exist and no annotations help, this description leaves significant gaps in essential context.

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 covers 100% of parameters with descriptions (source, destination, sms_body), including a format example for destination. The description adds no additional parameter information. Baseline of 3 is appropriate since the schema already documents the parameters effectively and the description does not need to compensate.

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 action (send SMS) and the resource (SMS via Voximplant), providing a specific verb and resource. However, it does not distinguish this from sibling tools like send_a2p_sms, which may have overlapping functionality. The purpose is clear but lacks sibling differentiation, hence a 4 rather than 5.

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?

There is no guidance on when to use this tool versus alternatives like send_a2p_sms or get_sms_history. The description merely states the action without any context, prerequisites, or exclusions. An agent would have to infer usage from the name alone, which is insufficient for deciding between this and similar tools.

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