send_sms

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

With no annotations provided, the description carries the full burden of disclosing behavioral traits. It does not mention any side effects, delivery guarantees, rate limits, cost implications, or response format. The description only states the action without any information that would help the agent anticipate consequences, making it severely lacking.

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 delivers the core action and target. It is not verbose and gets to the point quickly, aligning with the principle of front-loading key information. However, it is so brief that it sacrifices useful context, but this dimension rewards conciseness over completeness, so a 4 is appropriate.

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?

Given the tool has nested objects, no output schema, and no annotations, the description should provide substantial context to make up for these gaps. It only covers the basic purpose and leaves out usage scenarios, constraints, and expected behavior. The absence of any additional context makes it incomplete for safe and correct invocation.

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 schema already describes both parameters (to and content) with examples, giving 100% coverage. Since coverage is high, the baseline is 3. The description adds no additional meaning beyond what the schema provides, so it stays at baseline; it does not compensate for any ambiguity in the schema's cryptic formatting.

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), the resource (SMS), and the target (specific users). It is distinct from sibling tools like send_push, send_email, and send_whatsapp based on the channel name. However, it lacks an explicit differentiation from other send tools or a note about the 'direct' aspect, which would have earned a 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, prerequisites (e.g., user identity availability), or any exclusions. The phrase 'directly to specific users' hints at targeting, but it doesn't clearly explain the intended use case or contrast with sibling tools that might be more suitable for bulk or campaign messaging.

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