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retell_list_phone_numbers

Retrieve all phone numbers associated with your Retell AI account to manage voice and chat agents.

Instructions

List all phone numbers registered with your Retell account.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Implementation Reference

  • The handler case in the executeTool switch statement that performs a GET request to the Retell API endpoint /list-phone-numbers to list all registered phone numbers. No input arguments required.
    case "retell_list_phone_numbers":
      return retellRequest("/list-phone-numbers", "GET");
  • Tool schema definition including name, description, and empty input schema (no parameters required), part of the tools array used for tool listing and registration.
    {
      name: "retell_list_phone_numbers",
      description: "List all phone numbers registered with your Retell account.",
      inputSchema: {
        type: "object",
        properties: {}
      }
    },
  • src/index.ts:1283-1284 (registration)
    Registration of the tool listing handler that returns the tools array containing the retell_list_phone_numbers tool definition.
    server.setRequestHandler(ListToolsRequestSchema, async () => {
      return { tools };
Behavior2/5

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

No annotations are provided, so the description carries full burden. It states this is a listing operation, implying it's likely read-only and non-destructive, but doesn't explicitly confirm this or disclose other behavioral traits like pagination, rate limits, authentication requirements, or what data is returned. For a tool with zero annotation coverage, this leaves significant gaps.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, clear sentence that efficiently conveys the core purpose without any wasted words. It's appropriately sized for a simple listing tool and front-loads the essential information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's simplicity (0 parameters, no output schema), the description is minimally adequate but incomplete. It states what the tool does but lacks context about the return format, pagination, or behavioral constraints. With no annotations and no output schema, the description should provide more guidance on what to expect from the operation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has 0 parameters with 100% schema description coverage, so the schema fully documents the absence of inputs. The description appropriately doesn't mention parameters, which aligns with the schema. A baseline of 4 is applied since no parameters exist and the description doesn't need to compensate for any gaps.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action ('List all') and resource ('phone numbers registered with your Retell account'), providing a specific verb+resource combination. However, it doesn't explicitly differentiate from sibling tools like 'retell_get_phone_number' (singular) or 'retell_import_phone_number', which would be needed for a perfect score.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides no guidance on when to use this tool versus alternatives. It doesn't mention when this listing operation is appropriate compared to getting a specific phone number, importing numbers, or other related operations, leaving the agent without contextual usage instructions.

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

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