What is the Model Context Protocol (MCP)?

MCP is an open standard that allows developers to build secure, bidirectional connections between AI models and local or remote data sources.

Is my configuration secure?

Yes. FmtDev operates entirely locally. Your environment variables and sensitive API tokens never leave your browser.

Visual MCP Server Config Builder & Validator

FmtDev Visual MCP Config Builder is a free, local-first tool that lets you visually build and validate Model Context Protocol (MCP) configuration payloads for Claude Desktop and Cursor. Everything is computed directly in your browser with zero data logging or server transmissions.

Server Identifier

Runtime Command

Arguments (Comma-separated)

Environment Variables

Config File Location

~/Library/Application Support/Claude/claude_desktop_config.json

Compiled Output

{
  "mcpServers": {
    "my-custom-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-github"
      ],
      "env": {
        "GITHUB_PERSONAL_ACCESS_TOKEN": "ghp_yourTokenHere"
      }
    }
  }
}

Engineering Guides

Master This Tool

Deep-dive guides and tutorials for advanced users.

The Developer's Guide to Configuring Custom MCP Servers for Claude & Cursor

Configure custom MCP servers for Claude and Cursor with local-first JSON, stdio transport, and zero-error validation.

Read Guide

The JSON-RPC Renaissance: Protocol Powering 2026 AI Agents

Discover why JSON-RPC 2.0 is the foundational protocol for AI agent tool calling and the Model Context Protocol (MCP) instead of REST or GraphQL.

Read Guide

Understanding MCP Transport Layers: stdio vs. HTTP vs. WebSockets

A technical deep dive into Model Context Protocol (MCP) transport mechanisms. Compare stdio, HTTP with SSE, and WebSockets for secure AI agent integration.

Read Guide