@cerebro-nervio/mcp-kit

Minimal boilerplate toolkit for creating MCP (Model Context Protocol) servers.

Installation

pnpm add @cerebro-nervio/mcp-kit zod

Quick Start

import { z } from "zod";
import { defineMCP, defineTool, startServer } from "@cerebro-nervio/mcp-kit";

// Define a tool
const greet = defineTool({
  name: "greet",
  description: "Greets a user by name",
  schema: z.object({ name: z.string() }),
  run: async (input) => `Hello, ${input.name}!`,
});

// Define and start the MCP
startServer(defineMCP({
  name: "hello-mcp",
  version: "1.0.0",
  tools: [greet],
}));

API

defineTool(options)

Creates a tool definition.

defineTool({
  name: string,           // Tool identifier (kebab-case)
  description: string,    // Human-readable description
  schema?: ZodSchema,     // Input validation (optional)
  run: (input, ctx) => Promise<any>,  // Implementation
})

defineMCP(options)

Creates an MCP definition.

defineMCP({
  name: string,           // MCP identifier
  version?: string,       // SemVer version
  runtime?: string,       // Kit version constraint
  tools: ToolDefinition[],
})

startServer(mcp, options?)

Starts the MCP server.

startServer(mcp, {
  transport: "stdio",     // Transport type (default: stdio)
})

Context (ctx)

Every tool receives a context object:

ctx.log(message)          // Log to stderr
ctx.fs.read(path)         // Read file contents

Examples

MCPs live inside nerves at .nerve/mcp-servers/. See the base nerve for examples:

• packages/nerves/base/.nerve/mcp-servers/echo/ - Minimal MCP (<20 lines)
• packages/nerves/base/.nerve/mcp-servers/file-reader/ - File system tools

Each MCP is a publishable package. Install in other nerves via npm or copy the directory.

License

MIT