Vapi MCP Server

Instructions

Implementation Reference

• src/tools/phone-number.ts:26-30 (handler)

  The core handler logic that extracts phoneNumberId from input, fetches the phone number details using VapiClient, and returns the transformed output.

  createToolHandler(async (data) => {
    const phoneNumberId = data.phoneNumberId;
    const phoneNumber = await vapiClient.phoneNumbers.get(phoneNumberId);
    return transformPhoneNumberOutput(phoneNumber);
  })

• src/schemas/index.ts:309-311 (schema)

  Zod input schema defining the required phoneNumberId parameter for the tool.

  export const GetPhoneNumberInputSchema = z.object({
    phoneNumberId: z.string().describe('ID of the phone number to get'),
  });

• src/tools/phone-number.ts:22-31 (registration)

  Registers the get_phone_number tool on the MCP server with name, description, input schema, and wrapped handler function.

  server.tool(
    'get_phone_number',
    'Gets details of a specific phone number',
    GetPhoneNumberInputSchema.shape,
    createToolHandler(async (data) => {
      const phoneNumberId = data.phoneNumberId;
      const phoneNumber = await vapiClient.phoneNumbers.get(phoneNumberId);
      return transformPhoneNumberOutput(phoneNumber);
    })
  );

• src/transformers/index.ts:233-244 (helper)

  Helper function that transforms the raw Vapi phone number response into the standardized PhoneNumberOutputSchema format.

  export function transformPhoneNumberOutput(
    phoneNumber: any
  ): z.infer<typeof PhoneNumberOutputSchema> {
    return {
      id: phoneNumber.id,
      name: phoneNumber.name,
      createdAt: phoneNumber.createdAt,
      updatedAt: phoneNumber.updatedAt,
      phoneNumber: phoneNumber.number,
      status: phoneNumber.status,
    };
  }

• src/tools/utils.ts:30-41 (helper)

  Utility that wraps the raw handler with try-catch error handling and standardizes the response format to ToolResponse.

  export function createToolHandler<T>(
    handler: (params: T) => Promise<any>
  ): (params: T) => Promise<ToolResponse> {
    return async (params: T) => {
      try {
        const result = await handler(params);
        return createSuccessResponse(result);
      } catch (error) {
        return createErrorResponse(error);
      }
    };
  }