request_otp

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

Annotations already set destructiveHint: true, signaling side effects. The description adds no further behavioral context such as cost, rate limits, or the fact that this does not verify the OTP. It does add the 'Thai mobile number' constraint, but that is more of a target parameter trait than a behavioral disclosure.

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, front-loaded sentence that conveys the essential information with no redundancy. It is highly concise and every word contributes to the meaning.

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 one-parameter tool, the description is adequate. The schema covers the parameter format, annotations cover side effects, and the purpose is clear. It does not discuss return values, but there is no output schema, and the tool's action is straightforward. Minor improvements could mention that verification is handled elsewhere, but it is not necessary for basic use.

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 describes the only parameter 'msisdn' with format details (E.164 or domestic). The description merely repeats 'Thai mobile number' without adding new semantic meaning beyond the schema. With schema coverage at 100%, a baseline of 3 is appropriate.

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's function: 'Request an OTP code via SMS to a Thai mobile number.' It uses a specific verb ('request') and identifies the resource (OTP via SMS), and it distinguishes from siblings like request_email_otp and verify_otp.

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 implies when to use this tool (when an OTP is needed via SMS to a Thai number) but does not explicitly mention alternatives or when not to use it. Given the sibling tools list, some differentiation is inherent, but no direct guidance is provided.

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