Modality MCP Kit

Schema conversion utilities for MCP tool development with multi-library support. Provides universal JSON Schema conversion via xsschema and AITool-to-FastMCP transformation utilities.

Features

• Universal Schema Conversion: Convert Zod, Valibot, ArkType, Effect, and Sury schemas to JSON Schema via xsschema
• MCP Tool Registration: Transform AITool definitions to FastMCP-compatible format
• Type-Safe: Full TypeScript support with preserved schema types
• Lightweight: Minimal dependencies, focused on MCP tool development

Installation

npm install modality-mcp-kit
# or
bun add modality-mcp-kit

Usage

Schema Conversion

import { toJsonSchema } from "modality-mcp-kit";
import { z } from "zod";

const userSchema = z.object({
  id: z.string(),
  name: z.string(),
  age: z.number(),
});

const jsonSchema = toJsonSchema(userSchema);

MCP Tool Setup

import { setupAITools, ModalityFastMCP } from "modality-mcp-kit";
import { z } from "zod";

const mcp = new ModalityFastMCP();

const aiTools = {
  getUserById: {
    name: "get_user",
    description: "Get user by ID",
    inputSchema: z.object({ id: z.string() }),
    execute: async (args) => {
      return { id: args.id, name: "John" };
    },
  },
};

// Registers tools with MCP server and transforms inputSchema → parameters
setupAITools(aiTools, mcp);

API

toJsonSchema(schema)

Converts any supported schema (Zod, Valibot, ArkType, Effect, Sury) to JSON Schema.

setupAITools(aiTools, mcpServer?)

Transforms AITool definitions to FastMCP format:

• Converts inputSchema to parameters
• Uses key as name if not specified
• Registers with optional MCP server

ModalityFastMCP

FastMCP-compatible implementation with addTool() and getTools() methods.

Repository

• GitHub: https://github.com/react-atomic/modality
• NPM: https://www.npmjs.com/package/modality-mcp-kit

License

MIT