List phone numbers

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

Annotations already signal readOnly/idempotent/non-destructive, and the description adds value by disclosing the required OAuth scope and the specific related entities returned. This goes beyond the structured fields without contradicting them.

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?

Two compact sentences: the first states purpose and output scope, the second states auth. No filler or repeated schema details.

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?

Covers the essential purpose, returned context, auth requirement, and pagination parameters are documented in the schema. It does not describe the response envelope (e.g., next_cursor), but the schema's cursor descriptions and read-only annotations make this a minor gap.

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 the limit and cursor parameters are already fully documented. The description adds no additional parameter-level meaning, which is acceptable given the schema carries that burden.

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?

States a specific action ('List the phone numbers registered on this account') and names the resource plus the key related data returned (SIP trunk and agent). It clearly separates this from get_phone_number and the SIP trunk/list tools by its list-level scope.

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 gives clear context: it applies to phone numbers on the current account and lists all of them, which implies it is the right choice for enumeration rather than fetching a single number. It does not explicitly contrast with get_phone_number, so it stops just short of full guidance.

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