Rftools MCP Server

rftools-mcp

MCP server for rftools.io — 213 RF & electronics calculators + 13 server-side simulation tools for AI agents.

Give Claude, Cursor, or any MCP-compatible AI assistant access to validated engineering calculators and heavy server-side simulations. Microstrip impedance, link budgets, filter design, converter sizing, antenna patterns, and 200+ more calculators — plus NEC2 antenna simulation, FDTD, Monte Carlo, SMPS analysis, EMI estimation, and more, all callable as MCP tools.

Quick Start

Calculators work with no API key. For simulation tools, sign up at rftools.io and generate an API key from your dashboard.

Setup

Without API key — calculators only

All 210 calculators run locally with no sign-up required.

With API key — calculators + simulation tools

Sign up at rftools.io and generate an API key from your dashboard. Free accounts include 5 simulation runs/month. Pro: 100/month. API tier: 10,000/month.

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "rftools": {
      "command": "npx",
      "args": ["-y", "rftools-mcp"],
      "env": {
        "RFTOOLS_API_KEY": "rfc_your_key_here"
      }
    }
  }
}

Omit the env block to use calculators only. Restart Claude Desktop after saving.

Claude Code

claude mcp add rftools-mcp -- npx -y rftools-mcp

To add your API key:

claude mcp add rftools-mcp -e RFTOOLS_API_KEY=rfc_your_key_here -- npx -y rftools-mcp

Cursor

Add to .cursor/mcp.json in your project:

{
  "mcpServers": {
    "rftools": {
      "command": "npx",
      "args": ["-y", "rftools-mcp"],
      "env": {
        "RFTOOLS_API_KEY": "rfc_your_key_here"
      }
    }
  }
}

Windsurf

Add to ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "rftools": {
      "command": "npx",
      "args": ["-y", "rftools-mcp"],
      "env": {
        "RFTOOLS_API_KEY": "rfc_your_key_here"
      }
    }
  }
}

Tools

Calculator tools — no API key required

list_calculators

List available calculators, optionally filtered by category.

"List all RF calculators"
"What antenna calculators are available?"
"Show me power electronics calculators"

Parameters:

• category (optional): rf, pcb, power, signal, antenna, general, motor, protocol, emc, thermal, sensor, unit-conversion, audio

get_calculator_info

Get detailed info about a calculator — inputs with units/defaults, outputs, and the formula used.

"What inputs does the microstrip impedance calculator need?"
"Show me the buck converter calculator parameters"

Parameters:

• slug (required): Calculator identifier (e.g. "microstrip-impedance")

run_calculation

Run a calculator with specific inputs. Returns results with units and a link to the interactive version on rftools.io. Runs locally — instant, no quota consumed.

"Calculate microstrip impedance for a 0.3mm trace on 0.2mm Rogers RO4003C"
"What's the link budget for a 2.4 GHz link over 500m?"
"Size a buck converter: 12V in, 3.3V out, 2A"

Parameters:

• slug (required): Calculator identifier
• inputs (required): Object with input values, e.g. {"traceWidth": 0.3, "substrateHeight": 0.2}

---

Simulation tools — API key required

Server-side jobs that are too heavy for in-browser computation. Jobs run on shared compute (free tier) or a priority queue (Pro/API tier). Simulations typically complete in 15–120 seconds; queue wait may add additional time.

Quota: Free: 5 runs/month · Pro: 100/month · API tier: 10,000/month

list_simulation_tools

List all 13 available simulation tools with their jobType identifiers and parameter reference.

"What simulation tools are available?"
"Show me the RF simulation tools"

run_simulation

Submit a simulation job and wait for the result. Returns the full result JSON along with a link to the interactive results page on rftools.io.

"Synthesize a broadband matching network from 50Ω to 200Ω between 800–1200 MHz"
"Run a Monte Carlo tolerance analysis on a 2nd-order Butterworth low-pass filter at 1 GHz"
"Simulate a 3-element Yagi antenna at 144 MHz"
"Estimate radiated emissions from a 10cm trace carrying 50mA at 100 MHz"
"Run SMPS control loop stability analysis on my buck converter"

Parameters:

• jobType (required): Job type identifier — use list_simulation_tools to see all valid values
• params (required): Simulation parameters — use list_simulation_tools to see required params per job type

Available simulation tools:

Example Conversations

PCB Design

You: I need a 50-ohm microstrip on 1.6mm FR4 with 1oz copper. What trace width?

AI: Calls run_calculation with microstrip-impedance → A trace width of ~2.9mm gives you 50.2 Ω on 1.6mm FR4 (εr=4.2). View on rftools.io →

RF Link Budget

You: Will my 100mW 915 MHz LoRa link work at 2km with 3dBi antennas?

AI: Calls run_calculation with rf-link-budget → Received power: -72 dBm. With LoRa sensitivity at -137 dBm, you have 65 dB of link margin. Easily workable. View on rftools.io →

Power Electronics

You: Design a buck converter: 24V input, 5V output, 3A load, 500kHz switching.

AI: Calls run_calculation with buck-converter → Duty cycle: 20.8%, inductor: 17.4 μH, output cap: 22 μF. View on rftools.io →

All 213 Calculators

Why Use This Instead of Asking the AI to Calculate?

LLMs are unreliable at arithmetic. They may:

• Use simplified formulas that omit corrections (e.g. copper thickness in microstrip)
• Confuse units (mils vs mm, dBm vs dBW)
• Accumulate rounding errors
• Confidently present wrong answers

This MCP server calls the exact same validated calculator code that runs on rftools.io. Hammerstad-Jensen for microstrip, Friis for path loss, exact dB/linear conversions — real engineering formulas, not LLM approximations.

How It Works

Calculators are bundled as pure TypeScript functions — no API calls, no network latency, no rate limits. The AI calls the function directly and gets instant results.

AI Agent ←stdio→ rftools-mcp ←direct call→ calculator function

Simulation tools run server-side on rftools.io infrastructure (AWS Lambda + SQS + Fargate). The MCP server submits the job and polls until the result is ready, then returns the full result JSON inline.

AI Agent ←stdio→ rftools-mcp ←HTTPS + API key→ rftools.io API → SQS → worker
                                ←poll /jobs/{id}←
                                ←result JSON←

Machine-Readable Documentation

• rftools.io/llms.txt — Summary with API info and MCP setup
• rftools.io/llms-full.txt — Complete listing of all 203 calculators with inputs, outputs, units, and URLs

Links

• Website: rftools.io
• npm: npmjs.com/package/rftools-mcp
• Blog: rftools.io/blog
• Announcement: rftools.io Now Speaks MCP

License

MIT