vapi_get_phone_number

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

The description implies a read operation but does not disclose additional behaviors (e.g., authentication requirements, potential errors). With no annotations, the burden is higher, but for a simple get-by-ID tool, the description minimally suffices.

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 concise sentence with no unnecessary words. It front-loads the purpose effectively.

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 simplicity (one parameter, no output schema, no annotations), the description provides the essential information. However, it could be improved by briefly noting the return structure or typical usage context.

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 one parameter 'id' with no description and 0% schema coverage. The description adds no meaning beyond stating it is a specific phone number, which is already implied by the 'id' parameter requirement.

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 'Get a specific Vapi phone number' clearly states the action (get) and resource (phone number). Although it does not explicitly differentiate from siblings like list or buy, the name and description together imply retrieval of a single item.

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 guidance is provided. The description does not specify when to use this tool versus alternatives like vapi_list_phone_numbers or vapi_buy_phone_number, nor does it mention any prerequisites.

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