import { type Tool, tool } from '@supabase/mcp-utils';
import { z } from 'zod/v4';
type RequireKeys<Injected, Params> = {
[K in keyof Injected]: K extends keyof Params ? Injected[K] : never;
};
export type InjectableTool<
Params extends z.ZodObject,
Result = unknown,
Injected extends Partial<z.infer<Params>> = {},
> = Tool<Params, Result> & {
/**
* Optionally injects static parameter values into the tool's
* execute function and removes them from the parameter schema.
*
* Useful to scope tools to a specific project at config time
* without redefining the tool.
*/
inject?: Injected & RequireKeys<Injected, z.infer<Params>>;
};
export function injectableTool<
Params extends z.ZodObject,
Result,
Injected extends Partial<z.infer<Params>>,
>({
description,
annotations,
parameters,
inject,
execute,
}: InjectableTool<Params, Result, Injected>) {
// If all injected parameters are undefined, return the original tool
if (!inject || Object.values(inject).every((value) => value === undefined)) {
return tool({
description,
annotations,
parameters,
execute,
});
}
// Create a mask used to remove injected parameters from the schema
const mask = Object.fromEntries(
Object.keys(inject)
.filter((key) => inject[key as keyof Injected] !== undefined)
.map((key) => [key, true as const])
);
// Schema without injected parameters
const cleanParametersSchema = parameters.omit(mask);
// Wrapper that merges injected values with provided args
const executeWithInjection = async (
args: z.infer<typeof cleanParametersSchema>
) => {
return execute({ ...args, ...inject } as z.infer<Params>);
};
return tool({
description,
annotations,
parameters: cleanParametersSchema,
execute: executeWithInjection,
});
}
