Function: createTool()

function createTool<TContext, TName>(name): GroupedToolBuilder<TContext, Record<string, never>, TName>;

Defined in: packages/core/src/core/builder/GroupedToolBuilder.ts:138

Create a new grouped tool builder.

This is the recommended entry point for building MCP tools. Equivalent to new GroupedToolBuilder<TContext>(name) but more concise and idiomatic.

Type Parameters

Type Parameter	Default type	Description
TContext	void	Application context type passed to every handler. Use void (default) if your handlers don't need context.
TName extends string	string	-

Parameters

Parameter	Type	Description
name	TName	Tool name as it appears in the MCP tools/list response. Must be unique across all registered tools.

Returns

GroupedToolBuilder<TContext, Record<string, never>, TName>

A new GroupedToolBuilder configured with the given name.

Example

// Simple tool (no context)
const echo = createTool('echo')
    .action({
        name: 'say',
        schema: z.object({ message: z.string() }),
        handler: async (_ctx, args) => success(args.message),
    });

// With application context
const users = createTool<AppContext>('users')
    .description('User management')
    .use(requireAuth)
    .action({
        name: 'list',
        readOnly: true,
        handler: async (ctx, _args) => success(await ctx.db.users.findMany()),
    });

// With hierarchical groups
const platform = createTool<AppContext>('platform')
    .tags('core')
    .group('users', 'User management', g => {
        g.action({ name: 'list', readOnly: true, handler: listUsers });
    })
    .group('billing', 'Billing operations', g => {
        g.action({ name: 'refund', destructive: true, schema: refundSchema, handler: issueRefund });
    });

See

• GroupedToolBuilder for the full builder API
• ToolRegistry.register for tool registration