Wait for SMS

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

No annotations are provided, so the description carries the full burden. It discloses the blocking nature and timeout behavior, which is critical for an agent to know. However, it does not mention what happens on timeout (returns null, throws), whether the returned code is consumed, or any side effects such as the rental being invalidated. The description adds some behavioral context but leaves key details undisclosed.

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 short and front-loaded: the first sentence states exactly what the tool does. The second sentence provides context about its role in an automated flow, though it slightly overstates by implying it rents the number ('rent a number and get the code') when it only waits. Despite this minor inaccuracy, it's concise and efficient.

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?

With three parameters, no output schema, and no annotations, the description should clarify return behavior and edge cases. It does not explain what happens on timeout, the structure of the returned code, or whether the code is consumed. Given the tool's blocking nature and its placement among siblings (after rent_number), the description is adequate but leaves important gaps for an agent to operate fully.

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?

Schema description coverage is 100%, so each parameter (rentalId, timeoutMs, intervalMs) already has a clear description. The tool's description adds context about the purpose (waiting for SMS/OTP) but does not significantly clarify the parameters beyond what the schema provides. Thus, baseline 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: 'Block until the first SMS/OTP code arrives on a rental, or time out.' It uses a specific verb ('Block') and names the resource ('a rental'), with the purpose of retrieving an SMS/OTP code. This distinguishes it from siblings like list_services (listing) and rent_number (renting), making its role unambiguous.

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 usage context: 'The one-step way to rent a number and get the code in an automated flow.' This suggests using it after rent_number to wait for the code. However, it does not explicitly state when to use it versus alternatives (e.g., polling get_rental) or mention any exclusions, so guidance is only implicit.

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