listPhoneNumbers

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the read-only, account-scoped nature is covered. The description adds useful context about the two sources of numbers (shop-bought and imported), but does not disclose additional behavior such as pagination behavior, ordering, or output shape.

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 main sentence is concise, front-loaded, and packs meaningful scope information into one clause. The parenthetical '(Tags: Phone numbers)' adds minimal value, but the description overall is tight and well-structured.

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 paginated list tool with two optional, well-documented parameters and a readOnlyHint, the description is mostly complete. It does not describe return format, but the absence of an output schema and the simplicity of the operation make this a minor gap rather than a critical one.

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%, with both pageno and pagesize fully described in the input schema. The tool description adds no parameter-specific information, but the schema already carries that burden, making the baseline score of 3 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 uses a clear verb ('Retrieve') and resource ('the phone numbers on your account'), and explicitly includes both purchased and imported numbers. This makes the tool's purpose immediately distinguishable from related siblings like purchasePhoneNumber, importTwilioNumber, and searchPhoneNumbers.

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 this is the account-wide listing tool for phone numbers, but it does not explicitly say when to prefer it over searchPhoneNumbers or when not to use it. There is no mention of alternatives or exclusions, leaving usage context partially implied.

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