YedanYagami

Posted on Mar 11

I Built 9 MCP Servers with 49 AI Tools on Cloudflare Workers — Here's What I Learned

#ai #mcp #devtools #cloudflarechallenge

If you're building with Claude Code, Cursor, or Windsurf, you've probably heard of MCP — the Model Context Protocol that lets AI assistants use external tools. I went a bit overboard and built 9 production MCP servers with 49 tools, all running on Cloudflare Workers.

Here's what I learned, what went wrong, and what I'd do differently.

What I Built

Each server is a Cloudflare Worker handling JSON-RPC 2.0 requests via the MCP protocol. Zero cold starts, global edge deployment, and a generous free tier.

The 9 servers:

Server	Tools	What It Does
JSON Toolkit	6	Validate, format, diff, query, transform, schema generation
Regex Engine	5	Test, explain, build, replace, extract regex patterns
Color Palette	5	Convert, palette harmonies, WCAG contrast, Tailwind lookup
Timestamp	5	Unix/ISO convert, timezone, cron parse, duration format
Prompt Enhancer	5	Optimize, score, rewrite, system prompt generator
Intel	5	AI market intelligence, GitHub trends, tool comparison
Fortune	3	Zodiac horoscope, tarot readings (the fun one)
MoltBook	5	Markdown to HTML, SEO meta, translation, outlines
AgentForge	5	Side-by-side AI model comparison

The Architecture

Every server follows the same pattern:

export default {
  async fetch(request, env) {
    const url = new URL(request.url);

    // Landing page at /
    if (url.pathname === '/' && request.method === 'GET') {
      return new Response(landingHTML(), {
        headers: { 'Content-Type': 'text/html' }
      });
    }

    // MCP endpoint at /mcp
    if (url.pathname === '/mcp' && request.method === 'POST') {
      const body = await request.json();
      const { method, id, params } = body;

      switch (method) {
        case 'initialize':
          return mcpResponse(id, {
            protocolVersion: '2025-03-26',
            capabilities: { tools: {} },
            serverInfo: { name: 'my-server', version: '1.0.0' },
          });
        case 'tools/list':
          return mcpResponse(id, { tools: TOOLS });
        case 'tools/call':
          return handleToolCall(id, params, env);
      }
    }
  }
};

Key design decisions:

Streamable HTTP transport (not SSE) — simpler, works everywhere
KV-based rate limiting — 10-20 free calls/day per IP, Pro keys get 1000/day
In-memory fallback — if KV fails, degrade to 5 req/min instead of unlimited
Ecosystem hints — every tool response includes links to related tools on other servers

What I'd Do Differently

1. Start with fewer, better tools

I built 49 tools across 9 servers. Honestly, 3 really polished servers would have been more impactful than 9 decent ones. The JSON Toolkit and Regex Engine get the most actual usage.

2. Rate limiting from day one

I initially launched without rate limiting and got hammered by bots within hours. The KV-based rate limiter was a quick fix, but I should have designed it in from the start.

3. Landing pages matter more than you'd think

Each server has a landing page at / with a connect button and tool descriptions. These pages drive more signups than any README or marketplace listing.

The Stack

Runtime: Cloudflare Workers (V8 isolates, <50ms cold start)
Storage: D1 (SQLite), KV (key-value), Vectorize (vector search)
Protocol: MCP 2025-03-26 over JSON-RPC 2.0
Auth: API key via Authorization: Bearer header
Deployment: wrangler deploy — takes about 3 seconds

Total monthly cost for all 9 servers: $0-5 on the Workers paid plan. Cloudflare's free tier covers most of it.

Connect in 10 Seconds

Add any server to your MCP config:

{
  "mcpServers": {
    "json-toolkit": {
      "url": "https://json-toolkit-mcp.yagami8095.workers.dev/mcp"
    }
  }
}

That's it. Works with Claude Code, Cursor, Windsurf, and Cline.

Try It

All 9 servers are free to use with daily limits. No API key needed for the free tier.

GitHub — Full source code, MIT license
All 49 Tools — Try tools in your browser
Pro Access — $29/mo for 50K calls across all 9 servers

If you're building MCP servers, I wrote a MCP Starter Kit with the complete template I use for every server.

What MCP tools do you wish existed? I'm always looking for ideas for the next server.

DEV Community