List Vapi Phone Numbers

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions that the output includes IDs for use in calls, which adds some context, but fails to describe key behaviors like pagination, error handling, authentication needs, or rate limits. For a list operation with zero annotation coverage, this is a significant gap.

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 two concise sentences with zero waste, front-loading the core purpose and following with a practical usage tip. Every sentence earns its place by adding value without redundancy.

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's low complexity (one optional parameter) and high schema coverage, the description is adequate but incomplete. It lacks output details (no output schema provided) and behavioral context, which are important for a list operation. It meets minimum viability but has clear gaps in transparency.

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 schema description coverage is 100%, with the single parameter 'limit' well-documented in the schema. The description doesn't add any parameter-specific information beyond what the schema provides, so it meets the baseline for high schema coverage without compensating value.

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 clearly states the verb ('List') and resource ('all phone numbers in your Vapi account'), making the purpose specific and understandable. However, it doesn't explicitly differentiate from sibling tools like 'vapi_get_phone_number' (singular vs. plural), though the distinction is implied by the naming convention.

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 provides clear context for when to use this tool ('Use the IDs when creating calls'), which helps guide the agent. It doesn't specify when not to use it or name alternatives, but the guidance is practical and relevant to the tool's purpose.

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