Alternative to the official @modelcontextprotocol/sdk@v1 with:

• Standard Schema compatible validation library support
• WHATWG fetch standard support (Bun & Deno servers)
• Minimal dependencies (3 packages summing to 62KB vs 90 summing to 14MB)
• Result type builders

[!WARNING]

V2 of the official SDK will likely add support for all my changes. Waiting for that version to be released.

Supported Protocol Versions

Protocol Version	Supported?
2025-11-25	✅
2025-06-18	✅
2025-03-26	✅
2024-11-05	❌
draft	❌

Supported Features

MCP Feature	Supported?
Transports > stdio	❌
Transports > Streamable HTTP	✅
Prompts	✅
Resources	✅
Tools	✅
Authorization	❌
Basic Utilities > Cancellation	❌
Basic Utilities > Ping	✅
Basic Utilities > Progress	❌
Server Utilities > Completion	❌
Server Utilities > Logging	❌
Server Utilities > Pagination	❌

Goal here is to create a generalized MCP fetch function that I can host in my homelab and use in chats that supports Bun.

Installation

npm i @aklinker1/mcp-server-sdk
bun add @aklinker1/mcp-server-sdk
deno add @aklinker1/mcp-server-sdk

Quick Start

// main.ts

import {
  createMcpFetchTransport,
  definePrompt,
  defineTool,
  defineResourceTemplate,
} from "@aklinker1/mcp-server-sdk";
import z from "zod";

// Define your prompts, resources, and tools

const examplePrompt = definePrompt({
  argsSchema: z.object({
    param: z.string(),
  }),
  handler: async ({ args }) => {
    // ...
  },
});

const exampleResource = defineResourceTemplate({
  uriTemplate: "example://{id}",
  uriSchema: z.object({
    id: z.string(),
  }),
  handler: async ({ uri }) => {
    // ...
  },
});

const exampleTool = defineTool({
  inputSchema: z.object({
    param: z.string(),
  }),
  handler: async ({ input }) => {
    // ...
  },
});

// Create a server-side fetch function

const fetch = createMcpFetchTransport({
  toJsonSchema: z.toJSONSchema,
  prompts: {
    examplePrompt,
  },
  resources: {
    exampleResource,
  },
  tools: {
    exampleTool,
  },
});

// Serve the MCP server at http://localhost:3000

Bun.serve({ fetch });
// or
Deno.serve({ fetch });

Then run your server!

bun run main.ts
deno run --allow-net main.ts

MCP Inspector

Use the @modelcontextprotocol/inspector package to inspec your server:

bunx @modelcontextprotocol/inspector@latest --transport http --server-url http://localhost:3000