set_phone_number_allow_list

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

No annotations are provided, so the description must disclose side effects itself. It explicitly states 'Replaces the existing allow list' and 'Pass an empty list to clear it,' which are critical behavioral traits. This is a strong disclosure of mutation and destruction that goes beyond the tool name.

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 efficiently structured: a one-sentence purpose, two sentences of key behavior, and a formatted argument list that is easy to scan. No waste; each sentence adds value.

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?

The description covers the core behavior, arguments, and side effects. It does not explicitly mention edge cases like invalid numbers or provisioning prerequisites, but given the simple scope and presence of an output schema, it is nearly complete. A description of expected return/confirmation behavior could be added.

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 0%, so the description compensates by explaining each parameter: phone_number_id references list_phone_numbers and numbers requires E.164 format with an example. This adds meaning beyond the raw schema.

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 starts with a specific verb+resource: 'Set the allow list for a phone number' and clarifies the use case with 'only these numbers can send SMS to it.' It clearly distinguishes from sibling set_phone_number_block_list by semantic focus on allowing rather than blocking.

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 the use case of restricting incoming SMS to a phone number, but does not explicitly state when to use it versus alternatives like set_phone_number_block_list or set_phone_number_webhook. It provides clear context but lacks explicit exclusions or alternative references.

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