Grok Build

Bring xAI's Grok Build CLI into any MCP host as a peer reviewer, adversary, and consultant — alongside whatever main model you're already running.

grok-build-mcp is a small Model Context Protocol server that wraps the grok CLI. Your existing agent (Claude Code, Cursor, Cline, OpenClaw, …) can call into Grok for second-opinion code review, adversarial testing, or extended chat — without leaving its session.

繁體中文版：README.zh-TW.md

What you get

Four tools, all stateless, all stdout-only:

Tool	Use it for
grok_chat	One-shot prompt → Grok's reply
grok_review	Pass a unified diff (or auto-grab git diff main...HEAD) and get a per-dimension code review
grok_consult	Replay a message history for multi-turn — caller owns the thread
grok_challenge	Adversarial: ask Grok to find every bug, race, edge case, and security hole

Prerequisites

• Node.js ≥ 18
• The Grok CLI installed and authenticated:

  curl -fsSL https://x.ai/cli/install.sh | bash
  grok  # first run handles auth
  

Install

npm install -g grok-build-mcp
# or use npx — no install needed
npx grok-build-mcp

Wire it into your MCP host

Claude Code

claude mcp add grok npx -- grok-build-mcp

Or edit ~/.claude.json directly:

{
  "mcpServers": {
    "grok": {
      "command": "npx",
      "args": ["-y", "grok-build-mcp"]
    }
  }
}

Cursor

Create .cursor/mcp.json (project) or ~/.cursor/mcp.json (global):

{
  "mcpServers": {
    "grok": {
      "command": "npx",
      "args": ["-y", "grok-build-mcp"]
    }
  }
}

Cline (VS Code)

Settings → Cline → MCP Servers:

{
  "grok": {
    "command": "npx",
    "args": ["-y", "grok-build-mcp"]
  }
}

Any other MCP host

grok-build-mcp speaks plain stdio MCP. Point any client at npx -y grok-build-mcp and it works.

Tool reference

grok_chat

{ "prompt": "Explain consistent hashing in two sentences." }

Optional: model to override the default Grok model; timeout (seconds) to extend the per-call limit for long grok-4 reasoning. All four tools accept timeout.

grok_review

{ "base_ref": "main", "focus": "security" }

If diff is omitted, runs git diff <base_ref>...HEAD in cwd (defaults to your host's working directory). Returns a markdown review with verdict, per-dimension scores (correctness / readability / architecture / security / performance), and concrete fix-it items.

grok_consult

{
  "messages": [
    { "role": "system", "content": "You are a senior backend engineer." },
    { "role": "user", "content": "How would you cache this query?" },
    { "role": "assistant", "content": "Two options..." },
    { "role": "user", "content": "What's the failure mode of option 2?" }
  ]
}

The server is stateless — the caller passes the full thread each time. Most MCP hosts handle this naturally.

grok_challenge

{
  "code": "function transfer(from, to, amount) { from.balance -= amount; to.balance += amount; }",
  "context": "Node.js, called concurrently from HTTP handlers"
}

Returns severity-ranked issues (Critical / High / Medium / Low) with concrete reproductions and patches.

Configuration

Env var	Default	Purpose
GROK_MCP_BIN	grok	Path to the grok binary
GROK_MCP_TIMEOUT	300000	Default per-call timeout in milliseconds

Authentication and model defaults live in the Grok CLI itself (~/.grok/config.toml).

Timeouts

grok-4 is a reasoning model and long prompts routinely take longer than two minutes. The server's default per-call limit is 300s (5 min). You can change it three ways:

• Per call — pass timeout (seconds) to any tool: { "prompt": "...", "timeout": 600 }.
• Per server — set GROK_MCP_TIMEOUT (milliseconds) in the MCP server's env.
• Host side — the MCP host has its own request timeout that can fire before the server's. If calls still time out after raising the above, raise the host limit too. In Claude Code that's MCP_TIMEOUT (server startup) and MCP_TOOL_TIMEOUT (per tool call), both in milliseconds.

On timeout the error includes any partial output Grok produced before the deadline, so you don't lose a near-complete answer.

Roadmap

• v0.1 (this release): four stateless tools, stdio transport
• v0.2: server-side session persistence so grok_consult can take a conversation_id
• v0.3: streaming responses through MCP progress notifications

Development

git clone https://github.com/howardpen9/grok-mcp.git
cd grok-mcp
npm install
npm test
npm run build

License

MIT