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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does not mention that the tool only sends the code and does not verify it, nor does it note any side effects, requirements, or limitations. The single sentence is purely functional without safety or operational 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 description is a single, concise sentence that front-loads the primary action ('Send a 6-digit OTP verification code') and channel. Every word earns its place; there is no redundancy or unnecessary detail.

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 two-parameter tool, the description covers the core function, but lacks important context such as the separate verification step (verify_otp) and any delivery caveats. The absence of annotations and output schema makes this borderline, though the tool is simple enough that a 3 is reasonable.

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 already fully documents both parameters (to, brand) with descriptions, achieving 100% coverage. The tool description adds no additional meaning about parameter constraints, relationships, or formatting beyond what the schema provides, so the baseline of 3 applies.

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 tool sends a 6-digit OTP verification code via SMS or WhatsApp, which is a specific verb+resource. However, it does not explicitly distinguish itself from the sibling send_sms tool, leaving potential ambiguity about when to prefer this tool over a generic SMS sender.

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?

The description provides no guidance on when to use this tool versus alternatives like send_sms or verify_otp. It only states what it does, leaving the agent to infer usage from the tool name alone. No exclusions or preferred scenarios are mentioned.

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