Vapi MCP Server

Instructions

Implementation Reference

• src/tools/tool.ts:36-40 (handler)

  Core handler logic: transforms input data using transformToolInput, creates new tool via VapiClient.tools.create, transforms output with transformToolOutput.

  createToolHandler(async (data) => {
    const createToolDto = transformToolInput(data);
    const tool = await vapiClient.tools.create(createToolDto);
    return transformToolOutput(tool);
  })

• src/tools/tool.ts:32-41 (registration)

  Registers the 'create_tool' tool with the MCP server inside registerToolTools function, providing name, description, input schema, and handler.

  server.tool(
    'create_tool',
    'Creates a new Vapi tool',
    CreateToolInputSchema.shape,
    createToolHandler(async (data) => {
      const createToolDto = transformToolInput(data);
      const tool = await vapiClient.tools.create(createToolDto);
      return transformToolOutput(tool);
    })
  );

• src/schemas/index.ts:401-404 (schema)

  Input validation schema for create_tool, extending BaseToolConfigSchema and requiring tool type.

  export const CreateToolInputSchema = BaseToolConfigSchema.extend({
    type: z.enum(['sms', 'transferCall', 'function', 'apiRequest'])
      .describe('Type of the tool to create'),
  });

• src/tools/utils.ts:30-41 (helper)

  Utility that wraps any handler function with error handling, success/error response formatting for MCP tools.

  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);
      }
    };
  }