Wait for the SMS/OTP code

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

With no annotations provided, the description carries the full burden. It discloses that the tool blocks and can time out, which is useful. However, it does not specify what happens on timeout (error vs. empty result), what the return value is (the OTP code?), or that it polls at intervalMs. This leaves important behavior undocumented.

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 sentence that is concise and front-loaded with the key action ('Block until...'). Every word contributes to understanding the tool's core function, with no filler or repetition.

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?

Despite having only 3 parameters and no output schema, the description is too sparse. It omits the return value, timeout behavior, and relationship to sibling tools like rent_test_phone_number. Given the lack of annotations and output schema, the description should provide more context about what the caller can expect upon success or timeout.

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%, as each parameter has a description. The tool description itself adds no parameter details beyond stating the blocking/timeout behavior. Since the schema already explains the parameters well, a baseline score 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 states a specific action: 'Block until the first SMS/OTP code arrives on a phone rental, or time out.' It clearly identifies the resource (SMS/OTP code on a phone rental) and distinguishes itself from sibling tools like rent_test_phone_number (which creates the rental) and email-related tools.

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 phrase 'on a phone rental' implies the user must have already rented a phone, and the parameter description for rentalId ('returned by rent_test_phone_number') reinforces this prerequisite. However, the description does not explicitly state when to use this tool versus alternatives, nor does it mention what to do for email (e.g., use get_test_email_messages). Usage context is implied but not explicitly guided.

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