@mrxkun/mcfast-mcp

Ultra-fast code editing for AI agents powered by Mercury Coder Cloud.

Transform any MCP-enabled AI (Claude Code, Cursor, Windsurf, OpenCode) into a Priority Coder with intelligent multi-file editing capabilities.

🚀 Quick Start

1. Get Your Token

Visit mcfast.vercel.app to sign up and get your free MCFAST_TOKEN.

2. Install & Configure

Claude Code / Claude Desktop:

{
  "mcpServers": {
    "mcfast": {
      "command": "npx",
      "args": ["-y", "@mrxkun/mcfast-mcp"],
      "env": {
        "MCFAST_TOKEN": "mcfast_..."
      }
    }
  }
}

Cursor / Windsurf:

1. Settings → Features → MCP → Add New Server
2. Name: mcfast
3. Command: npx -y @mrxkun/mcfast-mcp
4. Environment: MCFAST_TOKEN=mcfast_...

VS Code / OpenCode:

{
  "mcp.servers": {
    "mcfast": {
      "command": "npx",
      "args": ["-y", "@mrxkun/mcfast-mcp"],
      "env": { "MCFAST_TOKEN": "mcfast_..." }
    }
  }
}

🛠️ Available Tools

apply_fast

Apply intelligent code edits to multiple files simultaneously.

Example:

instruction: "Add error handling to all fetch calls"
files: { "src/api.js": "<content>", "src/utils.js": "<content>" }
dryRun: false

Features:

• Automatic strategy selection (SEARCH_REPLACE, MULTI_EDIT, FULL_REWRITE)
• Deterministic diff generation
• Syntax-aware transformations

apply_search_replace

Fast targeted replacements for simple edits.

Example:

files: { "src/config.js": "<content>" }
search: "localhost:3000"
replace: "api.example.com"

search_code ⚡ (No API required)

Fast local pattern-based search. Works offline without token.

Example:

query: "fetchData"
files: { "src/api.js": "<content>" }
regex: false
contextLines: 2

reapply

Smart retry for failed/incomplete edits. Auto-retries up to 3 times with enhanced context.

Example:

instruction: "Add error handling to all fetch calls"
files: { "src/api.js": "<content>" }
errorContext: "Previous attempt missed the catch block"

🧠 MCP Prompts

mcfast provides built-in strategies for AI agents (Claude Desktop, etc) to use tools effectively:

• workflow_guide: Standard operating procedure (List -> Search -> Apply)
• refactor_plan: Strategy for safe, atomic code refactoring
• debug_investigation: Step-by-step debugging protocol

🔒 Privacy & Security

• Zero Persistence: Code is processed in-memory and discarded immediately
• Open Source Client: Audit the source at github.com/ndpmmo/mcfast. Current stable version: 1.1.0.
• Token Masking: Your MCFAST_TOKEN is never logged

💎 Priority Coder Mode

Upgrade to Priority Coder by adding your own Mercury API key in the dashboard settings:

• Dedicated bandwidth (no shared rate limits)
• Higher throughput for large codebases
• Direct access to Mercury Coder infrastructure

📚 Documentation

• Dashboard
• GitHub Repository
• Mercury Coder Docs

📜 License

MIT © mrxkun