List all phone numbers registered in your Vapi account.
List all Vapi phone numbers
This tool declares no required parameters. Add optional parameters from the input schema as needed.
{
"id": 1,
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"arguments": {},
"name": "vapi_list_phone_numbers"
}
}| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are present, so the description bears full responsibility for behavioral disclosure. It only states 'list all', implying a read operation without details on pagination, rate limits, or what 'all' encompasses (e.g., all numbers across the account). This is insufficient for an agent to anticipate behavior.
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, very concise. It contains no unnecessary words. However, it could be slightly expanded to improve completeness without sacrificing conciseness, hence a 4 rather than 5.
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?
Given the tool has no parameters or output schema, the description is minimal. It tells the agent the basic purpose but lacks information about return format (e.g., list of objects with IDs) or whether results are paginated. For a simple list tool, this is adequate but not fully complete.
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?
The input schema has zero parameters, and schema description coverage is 100% (no parameters to describe). Per guidelines, a baseline of 4 is appropriate. The description does not add parameter information, but none is needed.
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 specifies the verb 'list' and the resource 'phone numbers', clearly indicating the action. However, it does not distinguish from sibling tools like vapi_get_phone_number (single phone number) or vapi_buy_phone_number, which could be inferred but not explicitly stated.
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?
No usage guidelines are provided. The description does not explain when to use this tool versus alternatives such as vapi_get_phone_number for a specific number or vapi_buy_phone_number for purchasing. The agent receives no context on intended use cases or exclusions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.